[FSH SPECIAL TOPIC] Introduction to Analytical Techniques

[Music] your idea is waiting to be seen put it all on display with a beautiful website [Music] [Applause] [Music] yep okay [Music] are we already streaming on youtube yep we're streaming [Music] [Music] so [Music] so [Music] i think we can start i think we can start i'll just share the screens all right so uh good morning everyone and welcome to another webinar brought to you by the filipino science hub so this is a special topic for our filipino science hub research university uh we have introduction to analytical techniques that will be delivered by professor dindy boyles of louisiana state university so again good morning paul salahat uh especially full house putai in sazum and we have around 275 watchers say you should good morning so uh before we start our webinar let me just remind you of some of the of our request while we are conducting our webinar so kindly mute and uh turn off your video unless you have a question that will be uh later after the discussion and please no recording of the session because all of our videos will be posted in our youtube channel uh next slide please and uh after the discussion uh we will have a uh an open forum where there will be a 30-minute q question and answer session after the lecture and please reserve your question toward the end of the presentation you can type it in in our zoom chat box or youtube live comment section or you can always raise your hand here in zoom and uh wait for you to be recognized and you can uh ask your questions live later after the session and we will be also providing you with a certificate of participation we will post a google form link to issue a certificate of participation for this session in the zoom chat box and also in the youtube live comments and also in the youtube description we will be posting the uh google form link and uh please for you to get your certificate please subscribe to our youtube channel and also uh visit our uh website www.philsihub.com in order for you to get your certificates and also uh please like and uh follow our facebook page for future webinars all right so i'll give the floor to puya jeff to introduce the filipino science sub take it away yeah thank you marty okay um good morning everyone in the philippines so um it's actually evening here in the u.s i'm based in houston texas so my name is jeffrey buntin i'm actually a filipino scientist practicing um research essentially um in the us so uh for today i would like to introduce everyone to filipino science so um i believe that we actually have like a fairly mixed um set of audience right now some are kind of like regulars to our um online um events and but i think we do have like a fairly good um influx of uh new audience so um i would like to introduce filipino science up to um all of you um most more especially to those who are not really that familiar with so filipinos iron sub so this is actually an online platform that um i actually founded back in 2012 so when i was like a graduate student visiting the film um um studying in canada so um uh the main intention of this platform initially um when i started it and when i initiated it when i originated it in the in batanga city was that you know you will be wanted to be able to mentor um teachers when it comes to scientific research um but then you know i'm through time and you know with uh what happened last year you know when when the pandemic hits um the you know like the the globe and it's you know lockdowns where we're actually um implemented um we had to find a way um to adapt this platform um um as a means for our teachers to be able to adapt um to the new mode of teaching so um what we actually did was i you know like we we gathered you know like a few more of our trusted friends um you're actually seeing like um um some of them on the slide right now um so we have john marti mateo from the institute of plant breeding um from uplb we have our jp anya who's currently taking up his phd degree in chemistry at um in finland we have professor majon aguilar of up los banos um institute of chemistry we have janice varela who's a practicing research scientist in kansas and then professor ralph lauren alumia from from icu plb as well um um helping us out actually around this platform so um filter hub as um you know as an organization has one vision and um one mission and that is to promote um stem education um and also the culture of research um if you could go back please culture of research among um teachers and students um in the philippines so initially we were just targeting high school the high school demographic um on this platform but then you know like over the course of doing this we also um realize that you know there are some gaps in terms of um uh understanding of you know key stem areas um that need to be failed and then again at the same time even up at the high sc at the college level um research training is actually warranted and so these are some of the things that we want to actually address you know like you know um these are um all volunteer activities that we're trying to actually render um the filipino people um um you know um and you know this also enables for us to share you know everything we're learning um practicing um careers in the stem area um you know like with everyone from back home so if you could go uh go to the next slide please okay so so as we have mentioned earlier for promoting um stem culture and also um you know research amongst of philip uh students and teachers and you know that is actually um geared towards one vision so hopefully some people practice is the first world country so you would like to also be able to you know enable the philippines um to one day become a techn a technology and innovation driven country because you know like um much of the advances like in most of these um first world countries are actually driven by uh the fruits of uh science technology engineering you know the area of you know um mathematics and so how would we actually get there um we can actually get we um a path that we can we can actually see is by launching a new generation of filipino scientists and stem subject matter experts are targeting um students in as early as um at the high school level because you know if we can actually plant the seed of passion for stem um i i think we can um we can actually influence most of these students to pursue a career in the sciences and then you know um not everyone will become scientists not everyone will end up practicing um a technical career in the sciences but by participating in some of these um campaigns that we are offering um to the philippines filipino people for free um you know everyone will be um everyone will be able to learn you know how to come up to how to make um decisions that are actually based on information you know we would like to be able to build a wise uh filipino nation you know through these um um humble endeavors and so like at the moment we do have like two major programs um at filipino science hubs the first of which is felsi hub yeah filipino science of education and then the other one is still sci hub research university and in the succeeding slides we will actually be uh we will be um expounding on you know what these programs are really about next slide please okay so let me begin with phil's ihob education so um through this program we're actually trying to um enhance the competency and you know and to address any knowledge gap that our teachers might have not only when it comes to stem subject areas but when it comes to teaching um um in itself so um over the past ten months we have actually hosted a number of uh webinars that are actually um uh focused on sharing um best practices and and tips um on how to act to teach a stem um virtually or you know from a distance and so over the course of time we have actually gathered uh filipino academics from from from the us and from from from different parts of the world we gather them up together like in webinars um where they they share some of the learnings that they acquired from facts from from teaching um in major universities abroad so uh we do have a section in our website that covers all this you know we have all the recorded past webinars on um teaching that you can revisit and you know um take you know at the comforts of your home and you know and whenever it is most convenient to you so better than teaching webinars we have um listed up online resources that you can use and apply for when you are teaching um on stem subjects virtually next slide please um one of the most recent campaigns for that we launched um was uh creation of uh teaching modules um specific in the areas of biology chemistry and physics and we were we were lucky enough to recruit um very talented and passionate uh graduates and students of the of mathematics and science teaching um in uplb so we have um ing aguila iv ratio and mark marker test who all together are constructing teaching modules and also problem sets and sample exams um in these areas that i have mentioned so it's about every day we're releasing teaching modules that our teachers can use you know as guides for when they teach some of the topics that we're covering so um please check out all of these materials that we're releasing on our on our um online platform so we have we release them daily on our on facebook and then you can you can more easily browse over all of our teaching modules and practice problems and exams um on our website so you know during the time of the pandemic you know like when we cannot really teach face to face and we have some supplemental materials to help in um um making sure that the subject matters are actually delivered effectively um to our students so these are curated by by these three and where we're all um also looking at monitoring the content and making sure that they're really creating the impact or making the impact that we intend for them to deliver right i take it from here my name is jp onya i'm the research head of uh phil saihab and i would like to introduce phil sahab research university to everyone and as dr jeffrey said this is our campaign to introduce the the research culture among our high school and college students so phil hubb research university is a free free research training program that we offer uh consisting of eight mandatory courses uh which which includes uh research ideation experimental design thesis writing data processing to name a few so this is open for high school and college students and these will all include the tips and best practices for for research and uh we have made this uh a very friendly uh introduction to to research my introduce different aspects of research teachers ministers research projects i mean science research projects uh to our students so we already have um something to add yeah so so one day for example we encourage the teachers for to take these courses with the students that you're mentoring and research because um wherever you go um research um is usu research um becomes successful if it's if it becomes a collaborative work you know between between mentors and students also if you learn um these best practices and you know like some fundamental approaches to research um you can actually um build on on the dynamics that you can that's that you that you that you initiate you know as you take these courses for so um [Music] all you have to follow steps one to ten yeah yeah we are also infusing um learnings that we learned from you know um from doing research ourselves so i've been practicing research for about 16 years now so and to make your lives much easier when you do your research so i highly encourage you to take these courses these are all for free and one very important thing for us that we are trying to build and jp it can become it's gonna be covering this soon we're trying to build the community through this program so yep so we have already uh have recorded or undertook already three recorded training courses for phil sciab research university the first one was for research ideation the second one is for literature review and just last month we had the course number three which is uh experimental design and uh i do i would just like to take this opportunity to uh uh like advertise our fourth course which is happening uh two weeks from now um which is about uh research how to develop a research proposal which will be delivered by our by our ceo dr jeffrey bonkin so you know because these are all free these are all out on youtube so uh we have devised a google classroom for this and uh we have uh put all the descript the description in the in the youtube videos uh video description google classroom because we there we can access all of the materials for uh philsaya research university and uh be able to complete the course certificate of completion complete or participate core system research university which is uh eight mandatory courses so inania and puna minla teachers and students uh to take part in this campaign and uh we all hope to see you in in our next activities tito possibility of research university anything to add dr jeff i think that's good that's good thank you yep uh of course uh we uh apart from the the mandatory uh topics we also have special topics like what we have today um we already had uh two special topics which was about nanotechnology and uh and the other one was about uh all the the the analysis a polymer uh the thermal uh thermal properties of polymers so ethernet law introduction to analytical techniques we noticed that a lot of a lot of students and teachers are clamoring for for this case practical analytical techniques that everybody uses for for their thesis or research projects so and this and this will also provide you guys with a glimpse of anybody [Music] you're working on a research idea so if you don't know how if you don't know how to identify um a suitable analytical method for your for your experimental problems i think in part this might this this will really help you yep and i would like to also to advertise our next uh special topic which is happening in march uh this research ideas that we can do uh that we can investigate at home and uh this is very uh very very important especially in this time now of pandemic research ideas we can easily do do at home and also uh dr jeffrey will add on some the the aspects of the brainstorming process yeah so this is happening in march yeah so everything is uh uh registration youtube and all of our channels so please uh keep an eye on that okay all right thank you huya jeff and we jp for introducing the filipino science up so uh for today our speaker let me it is my honor to introduce our speaker for today uh our featured speaker is doctor din bu boyles uh quality and technical manager that is based in kentucky united states so mom dnb finished her bs chemistry degree at uplb and after awards she became a faculty member of the institute of chemistry before going to the united states to pursue her phd degree at the university of houston and her research focus is more is from is her research focus is detection of molecules and cells labeled with magnetic magnetic particles using an atomic magnetometer so she was an assistant professor of chemistry at louisiana state university in alexandria and also a quality assurance and technical manager at a top paint and coating company operating in the global market she also served as a quality consultant for a biopolymer manufacturing company and also with diverse industrial experience in enviro environmental industry biotechnology and food chemical so next slide please go gp so for today she will introduce you to some analytical techniques that is uh important in the field of chemistry so without further ado i'll give you doctor din b you boy mom dmd take it away thank you for that very kind introduction uh marty um i just want to congratulate everyone and filipino science have on your continuing success my reach uh in in our own country and all over the world so it's a it's an honor to be here this morning um like what uh marty said in the introduction i will be talking about introduction to analytical techniques so let me just share my screen real quick okay so from the title itself i will be giving an overview of your common commonly used analytical techniques in academia as well as in industrial applications so just a brief overview of this webinar the first section is a discussion of levels different levels of analytical methodology and then i will be talking about the four uh commonly used techniques which are gravimetry tetrametry spectroscopy and chromatography let me throw some definitions also these terms you will hear all throughout the presentation so you have analyte which is the component of interest in the sample and then matrix is the remainder of the sample and now here are some examples so everything that's highlighted in yellow are your analyte and everything highlighted in blue is matrix so for example you have lead in drinking water uh you want to know the concentration of lead so let is the analyte and then the remaining of the sample remainder of the sample is water so you have a water matrix okay for so for example um your task is to know or come up with a method to determine the concentration of lead in drinking water so how are we going to approach this task this is best approach by knowing the different levels of analytical methodology so the very first step is to know the available techniques for this type of analytical task so um for leading water there are many techniques available and one of them is graphite furnace atomic absorption spectroscopy or gfas and we will be talking about this briefly in the next section of this webinar but depending on your goals you select the techniques or technique that that will suit your purposes but what is the technique it's any chemical or physical principle that can be used to study an analyte so in spectroscopy specifically absorption spectroscopy it involves atomization of the sample and then absorption of light to create the signal for your spectra so the combination of both uh principles uh collectively is called spectroscopy so now that you have selected your technique um the second step is to to determine the method for um for lead in water so what is the method it's the application of a technique for a specific analyte in a specific matrix so the method that you will use for lead in water will be different from the method that you will use if you know lead is in soil or that is in blood and um we use different methods for these because you have different matrices because if you have different matrices that means you have different interferences so now that you've selected your method then you can write a set of instructions so specific steps telling you how to carry out that particular method for that sample so if you're doing research you can right come up with your own procedure again based on your goals and and make sure that you can justify the steps that you include in the procedure but if you're working for um just for a standard testing of lead and water there are different procedures available such such as the procedures by afa or american public health association and astm or american society for testing and materials the last level is uh protocols so um you have to ask uh the question okay i need to determine lead in uh drinking water but will my data be submitted to a regulatory agency or will it be used for a court case so if that's the case you have to learn or you have to know the protocol set by epa for example or environmental protection agency so if you um for the protocols you have to follow it to a team you cannot deviate from it and otherwise these agencies will not um not accept your result so uh protocols include you know other requirements for calibration curves uh how do you collect your sample how do you preserve your sample uh how do you validate results things of that nature so um with this big picture hopefully um i was a hopefully i was able to share the importance of understanding and the analytical technique okay so let me uh share with you some common analytical techniques which can be categorized into two broad categories the first category is called total analytical techniques these are your classical uh techniques and they are gravimetry or titratory and these in this techniques you measure either the mass or the volume the second group or category are your concentration techniques so from the name itself uh you measure the concentration and normally it's based from the from an electrical or optical signal and these types of techniques uh require specialized instrument and sometimes that's why sometimes it's called they are called instrumental so you have spectroscopy and chromatography okay so let's uh talk about gravimetry so in gravimetry a measurement of mass or a change in mass provides the quantitative information about the analyte so the general procedure looks something like this um first step is you prepared the solution containing the analyte and then you would want to separate the analyte from the sample and then you dry and weigh the isolated analyte and then finally from the mass of the analyte you perform your calculations so here are some of the most common equipment or materials needed for gravimetry of course you need a balance it could be analytical or top loading and we know analytical is more sensitive than the top loading because it could read up to four or five decimal places and then you have the sample holders uh you have crucibles evaporating dish and aluminum pans to hold your filter so the crucibles are normally used for if you need to heat your sample at very high temperatures and then you need to have filtration set up so it could be a gravity filtration setup or a suction filtration set up so the gravity filtration obviously from the term from the term itself you allow you let the gravity separate the liquid portion from the solid portion of your mixture whereas suction filtration you utilize a vacuum pump to create a vacuum in the flask and it aids in infiltration and making it faster compared to the gravity filtration of course you need a lab event to dry your um your analyte if you need to ignite your sample at high temperatures i normally use a muffled furnace and then finally you have uh desiccators where you could cool your analytes especially if they are moisture sensitive so there are three types of gravimetry that i will be sharing with you this morning the first one is particularly gravimetry the second is volatilization gravimetry and the third one is precipitation gravimetry so in a particular gravimetry your analyte is already in a particular form so because of that it's easier to separate it from your matrix and so therefore the separation step is either filtration or extraction of the analyte from the sample so one common application of particular gravimetry is the determination of total suspended solids in treated waste water so in this method you use a glass fiber filter to retain your suspended solids and then after filtration you dry it to a constant weight at 103 to 105 celsius so this method is was published by ava uh it's called method 25 2540d and standard methods for the examination of waters and wastewaters and so normally when you do this kind of uh test or this method you have many many samples so it's impractical to just have one suction filtration set up so normally you would have a manifold where you have multiple suction filtration setup attached to a vacuum pump another application of particulate gravimetry is the determination of crude total fat and chocolate normal procedure includes extraction of the sample with organic solvent such as either for 16 hours then you let the extract evaporate to dryness at 95 to 100 celsius and you weigh it and the last application that i am presenting under particular gravimetry is the measurement of total suspended particles in atmosphere so you have a high volume sampler with a pre-weight filter and normally you collect the air sample for 24 hours and after that you measure the filter and the mass of the suspended particles will give you the concentration of tsb in the in the atmosphere all right so that's it for a particular particulate gravimetry so let's move on to volatilization graphing metering so in volatilization gravimetry thermal or chemical energy decomposes the sample containing the analyte usual measurements are the mass of residue remaining after decomposition the mass of volatile product collected using a suitable trap and the change in mass due to the loss of volatile material so from the name itself the separation step for this type of gravumentary is the volatilization of the solution containing the analyte so a known application application of volatilization gravimetry is the determination of inorganic ash content of polymers in general i'm just giving pululan as an example because i've worked on it for many years so the task is called residue on ignition test where you have a sample and you hydrolyze it using hot sulfuric acid and then you ignite it to high temperatures to 500 to 600 celsius for three to four hours so the remaining ash is cold then weight and this test method is uh you can find it on usb or united states pharmacopoeia in 281. pololan is a biopolymer that has film forming properties typically used in making breath strips and vegan capsules so these particular tests will help determine if you're for forming a stable film you don't want a lot of inorganic inorganics in your puluolan another application of this type of gravimetry is called loss on drying tests for drug substances so uh this is published uh under usb 731 where um you crush at least four capsules or tablets and then you let it dry for extended periods of time under vacuum so it depends on the motor what's called monograph or what the requirements are for that particular of uh drug substance but here you're almost measuring the moisture content but you're not calling it moisture content because in the process of drying there are other substances that are also lost um yeah during during the the drying process all right that's it for volatilization gravimetry uh the the third type of gravimetry is called precipitation gravimetry so in this type of gravumentary uh you you use a precipitating reagent hello yeah okay thank you welcome for us uh to those who just joined in uh we're yes so uh like i said the uh recipient precipitation gravimetry you uh use a precipitating reagent or precipitant uh to a solution containing our analyte and most methods in most precipitation gravimetry it's a simple double displacement reaction between the analyte and the precipitant so before you filter the the mixture containing the analyte you have to add the precipitating agent first and so for example you want to measure the percent barium in a solution of barium nitrate so what you you do is you mix it with potassium chromate or your precipitant and what you get is a yellow precipitate which is barium chromate and potassium nitrate so these products are based on the double displacement displacement reaction between potassium chromate and bearing nitrate dr lindy i just have like one um one i guess it's like a very good opportunity for us to emphasize to our student participants that it is like for you to be able to um design an experiment that would involve precipitation gravimetry it is very important for you to be very knowledgeable of solubility rules exactly thank you that's right that's uh that's so true so this type of gravimetry is based on uh solubility rules just like what dr jeff uh had said thanks for that so yeah it's a long uh it looks like a long process but um once you have the the mass of your precipitate you can perform what's called stoichiometric calculations in order to achieve the um your goal which is percent barium as percent weight overweight so in precipitation gravimetry has been replaced by more advanced uh techniques however you can still uh use it in some applications like uh assessment of the accuracy of other methods of analysis it can still be used to verify the composition of some standard reference materials and it can be used for a qualitative test identification of inorganic and organic analytes okay so that's it for gravimetry um so let's move on to the next technique which is uh titrimetry so in titrimetry um what you're measuring is uh volume so that's that's what serves as the analytical signal some terms that we need to review uh include titration which is just the process of delivering a solution of known concentration into another solution which is called the titrand so the one that has a known concentration is called the tite trend so um note that titrand normally contains the analyte but sometimes uh the titrant or the the the one that is of known concentration is the analyte and then another term is equivalence point so this is the point where um enough titrant has been added to your analyte and uh it's also called sometimes called stoichiometric point so physically sometimes it's difficult to see if your equivalence point has been reached so most of the time we use what's called an indicator so it's a substance that changes color in response to a chemical change so when when the indicator changes color that means you have reached the end point and ideally you want the end point to coincide with your equivalence point and then finally you have stoichiometric ratio so it's the mole ratio between the titrant and the analyte based on a balanced chemical reaction common equipment or materials needed include burette so buret uh normally in the lab you use the 50 mlb red class a for uh to get accurate measurements and then for your receiving container you have either erlenmeyer flask or a beaker and of course you need something for your buret right to uh to hold so you need an iron stand and clamp and sometimes your iron stand iron stand has a white background which is also sometimes needed for your titration to clearly see the the first sign of color change by your indicator and of course you have the automated titration set up where the titrant is pumped into the titrand at a fixed flow rate and uh the the ph of the titrant is monitored as you uh as you add more uh titrant so this is good if you all uh want to get titration curves between the titrant and the analyte so general procedure you prepare the analyte and add the indicator if applicable because there are some titrations that don't need indicators because your titrants are self-indicating the next step is to prepare your titrant so you load your solution into the burette make sure the the meniscus is on the where it should be and a part of part of the titrant preparation is called standardization where um you you determine the actual or the exact concentration of your titrant for more accurate uh calculations and then you gradually add your titrant to your analyte until the end point is reached and then of course you perform your calculations so at the equivalence point or stoichiometric point um we know that the um the moles of the titrand can be calculated based on the molarity of the titrand normally obtained by a standardization times the volume of the titrant to reach the equivalence point once you know the moles of the titrant you can relate that to the moles or you can get the moles of the analyte by multiplying it by the mole ratio or the stoichiometric ratio between the titrand and the analyte and then finally the end goal is to calculate for the molarity of the analyte so that's simply the moles of analyte divided by the volume of analyte in liters okay so um we will be talking about three types of tetrametry in this webinar the first one is acid base titrometry the second is complexometric taxometry and the third one is redox titrimetry so acid-base cytometry from from the name itself you um you titrate uh it's based on an acid-base reaction basically so um you have an acid of known concentration and you neutralize it with a base of unknown concentration and the titration progress can be monitored by visual indicators ph electrodes or both so a very common indicator used for acid-base titrometry is phenolphthalein where in acidic form it's colorless and in basic form it's pink so here's just an animation of an acid-base titration with phenolphthalein and you will see that uh during titration you will see flashes of pink and the end goal is for that color to linger or permanent color during your measurement so actually you want a faint pink uh color i think this color is a little too dark for an end point but um that's that's what you need uh that's what you want to achieve during an acid-base titration so a typical example of acid-base titration is the um if you have a strong acid like hcl and you titrate it with a strong base like sodium hydroxide so at equivalence point um you see that you form sodium fluoride and water or salt and based on this equation we can say that one mole of hydrochloric acid is equal to one mole of sodium hydroxide so you can use the stoichiometric ratio to calculate for the molarity of hcl also with these products it's safe to say that the resulting solution equivalence point has a ph of seven so um just like what i mentioned earlier you can monitor the uh the progress of titration using those automated titrators um by monitoring the ph um based on the volume of titrant added so like i mentioned a strong acid and a strong base titration will have a ph 7 at the equivalence point so this is not always the case in terms of ph so for example you're titrating a weak base like ammonia with a strong acid hcl and based on the uh this blue curve right here the actual ph at equivalence point is below seven same applies for uh if you're titrating a weak acid like acidic acid with a strong base sodium hydroxide the equivalence point is above seven so with this information um you need to know you need to select the correct indicator that matches these equivalence point because otherwise um if you use an indicator that is not within this range then uh you will not have an accurate uh measurement so here is just a list of acid-base indicators that are also used for acid-base titration so acid-base titration um in general titration has been replaced with more advanced techniques but again you can still use this uh depending on your the availability of your resources so one application is uh the standardization of titrants and this is a determination of exact or more accurate concentration of your titrands commonly known primary standard is potassium hydrogen saline or khp and it's used for the standardization of basic titrants another application of acid-base cytometry is your killdell analysis for organic nitrogen and with this analysis um there are some of the analytes include caffeine and saccharin in pharmaceutical products proteins in foods analysis of nitrogen in fertilizers sludges and sediments so here's just the basic schematic of a kilda analysis so before you do that your titration there are a few steps that you need to do first is digestion and then neutralization and distillation so from this process um you recover the nitrogen as ammonium borate and that's what you titrate against standard hcl right that's it for acid-base uh titrametry yep dr dendy um there's just like one thing that uh i think we can we can also um add to uh uh digimetry uh to activate that diagram so for for all of these analytical techniques that um dr dendi um has actually been talking about it is very important that okay you're familiar with the type of chemical reaction that is involved and whenever you're doing calculations um related to you know like a specific technique you always have to be working on a balanced chemical equation so you know you're the stoichiometric ratios between um your reactants and also like the products that you are measuring um in the process you have to make sure that uh those are um according to a well-balanced and um solution so that's like one of the points for for high school students and and college students as well one hundred percent agree dr jeff all right so um let's move on to uh complex symmetric titrimetry so in this type of titration um you involve a simple ion um that is transformed into a complex ion so you use indicators and also you can monitor with uh with ph so here's a general equation um typically what you your analyte for complexometric titration are metal ions so what you do is you add a what's called a ligand to form a complex with uh with the metal and like just like what uh dr jeff mcqueen said it's important that the equation is is balanced or the equation has the correct coefficients in front of these uh participating species in a chemical reaction so a a very common uh collating agent or a ligand is a is called adta so ethylenediamine tetra acetic acid and as you can see from here um it's the the complex uh that that is formed has like six spots to form a complex with a metal ion so here's a list of uh commonly used indicator for uh at the titration i'm mostly familiar with kalama guide and arrived from black tea so just like your acid base indicators these indicators are ph dependent so take for example um you want to analyze uh barium ions so initially you the the barium is bound to uh to the indicator which in this case is the arrival of black tea and then um and then your eta is your titrant so um the more enter you add to your mixture uh the the complex um changes so the barium becomes more attached to to edta because it's it's a certain amount of edta um the complex of formation is more favorable for barium edta so at equivalence point um all the barium that's available will form a complex with adta which is a colorless complex and when that happens it releases your indicator from barium and the indicator changes from red or white red to steel blue so here's just a picture of uh what it looks like during a an enter titration with a rhyochrome black tea so just like what i mentioned um complex symmetric titration has been replaced with more advanced techniques but there is still an acceptable test method for um using this type technique it's the total determination of total hardness in water with adta so same concept from the previous slide except your analyte is calcium or magnesium so as you can see here your initial color is wine red and at at stoichiometric point or at just right after the stoichiometric point uh you form a steel blue solution okay so the last uh type of titrate titrimetry is uh is redox tytrimetry so in redox diagram you involve what's called the oxidation reduction reduction reactions between the titrant and the analyte so a reaction that everyone dreads [Laughter] yeah yeah i know like you know there's a bunch of i mean this is this the topic of redux are reactions and balancing redux reactions it's something that happens but unfortunately most students um don't really like don't enjoy so um you just have to count electrons this is actually you know various you know it's quite similar to just balancing um acid and based reactions right your your currency for acids and bases are protons in this case your currency is um electrons that's correct so because there are some redox balancing redox uh equations that can they can get complicated it wasn't my favorite in grad school in college for sure but yeah we actually have a lecture video yeah we have a lecture video on how to balance redux reactions so you guys should check that out okay good but thankfully i'm just talking about introduction introduction to these techniques i don't need to get in depth in this topic but generally speaking so uh in the redox reaction uh you have um just like what dr urban queen said uh your uh your currency is the the electrons so in a chemical reaction in a redox reaction um one substance loses the electron and the other gains that electron so when you lose an electron the process is called oxidation and that means the the substance was oxidized and then the opposite is the electron gain which is reduction so that means the substance was reduced so the substance that underwent oxidation is the reducing agent and then the substance that went reduction is the oxidizing agent so in this type of titration um you can still use metal and um not metal but some sort of indicator but um sometimes the titrant can serve as its own indicator especially if the oxidized and the reduced forms are significantly significantly different in color so here's just a list of indicators that you could use for a redox titration and if you are taking analytical courses these are the the common redox titration that you will uh you will encounter so it's called permanganometry where you use the permanganous to measure the amount of analyzer that's permanganate is your titrant examples of analytes are iron ion manganese oxalate nitrite and hydrogen peroxide and then of course you have iodimetry and iodimetry so with one with an o in the middle and the other with an i um the iodometry is the indirect titration of of your analyte with excess iodide and then you use a starch indicator to determine the endpoint at the end of the titration and then iodimetry is a direct titration of the analyte which serves as the resisting agent and it's titrated with a standard iodine solution so like other type of titrations you have more advanced techniques for for determining your analytes your anions and cations but um they're still an acceptable method for the determination of total chlorine residual and so this picture just tells you the color changes during the um iodometric titration so you first you form a brown uh solution which contains a tri iodide and then you titrate it with sodium tin sulfate which converts your tri iodide to iodine ions then you add the starch which forms a purple starch i3 minus complex and then just a few drops of your titrand which is sodium thiosulfate uh will give you a colorless solution so there are several equations for for this type of redox that we will not be talking about but um again uh thank you dr jeff for your emphasis uh make sure your equations are balanced when whenever you're calculating like patients with with this type of titration and then another practical application of a redox titrometry is the analysis of ascorbic acid uh by iodimetry so that's all i have for the classical techniques dr jeff do you want to add something else um i think that's mostly it just emphasis on um balanced chemical equations so you know whether it's the that you're doing gravimetry um you're you're you're you're recovering your analyte um using a precipitant um it's very important that you know the cytometry between between your analytes and your precipitating agent and whether it be for acid-base titration complex symmetric titration or redux titration the heart of everything that you're doing is um a balanced chemical equation so don't take those chemical reactions that your teachers our people are are teaching you um in in your classes because that can be your bible for whatever it is that you're doing good point very good point [Laughter] yep okay so are we good to move on or you need a five minute do we get to have a break or uh yeah i i think i think i think we can actually have like just like a five minute break for people because you know we have the second half of the shop and for for yeah for doctors also be able to uh have a couple of steps of her tea because i know you know speaking for an hour could actually be done on the throat yeah i mean don't don't drop i mean just yeah i mean like well we'll be back in just like in five minutes so okay stay thinking okay yep yes so we will have a five minute uh bio break so if you want to go to the bathroom or comfort room or yeah i think i mean i i think like during that period i mean like we can even like start answering questions but you might you might be able to answer marcy no [Laughter] let's uh let's give it to mom dindy who's the expert yeah yeah uh jjp do you have something to uh play yeah you can play like you know some video you want is that a video about excels i have research university yes voila okay the one on youtube [Music] around 500 participants in youtube and 100 here in zoom so a total of 600 plus participants thank you for yeah joining us today please drop your so we do have an upcoming webinar on um how to develop effective research proposals so for for teachers out there both at the high school and college level if you are not really that confident in um writing up research proposals this is for you and this is also fair for the students so uh we will be covering um some of like the fun steps and putting together a research proposal and not only that we will also be providing tips on how to effectively pitch your scientific idea because you know like the research for postal step does not stop at the writing page so you have to be able to communicate um your ideas your objectives um and convince people that you know um perhaps the jet idea is worth funding um we will also be inviting people who have had experiences writing a proposal at the high school college and even you know um um at the college level and even those who have submitted proposals to the osc so we began to combine different types of research projects so that's happening on february 28th 20th um saturday um so it's exactly two weeks from now and then um also um in the same session we will be launching filipino science subs lions then so it is an online competition for the best scientific uh research idea so for sip so this is gonna be at the high school level so essentially if you're familiar with the show like um shark tank um this is kind of like similar to that so um we are soliciting for research proposals and essentially we will be inviting three scientists like from different parts of the world to actually screen those ideas and that you know they're who we consider our lions you're going to have to present your ideas to this expert panel of judges and you're going to have to convince them that yours is actually the best idea there is and um we're going to be giving up a 10 000 peso cash prize for the best science idea um that's which you can use um you know to um fund you know some of your um some of your research project um expenses and then 22nd party the one that we have so we will be running a workshop so um teachers and students and they don't know how to start a research project um in the middle of a pandemic so marty will actually be sharing um some practical ideas or or some some ideas that you can you can you can um explore at the comforts of your home and you know um come and then for you to be able to ultimately come up with the research project and then you know session fundamental on the same day um your guides in terms of like how you proceed with uh the brainstorming process so body if you're working as part of a team how do you screen say 10 different ideas from 10 different members where do you start how do you set criteria the right criteria to pick the right topic are you the best the best topic that um the best topic for a research project so your workshop will give you some practical guides on how to go about these activities that are very critical and crucial for um starting your research project yeah march 20 yeah so march 20th february 20th and march 20th yeah yeah you nasa a couple more special topics so we have um nasa um i'm discussing i think is it uh cem um imaging so essentially it's microscopy we do have a couple of other sessions lined up um so in in in march uh we'll be featuring um um um uh philippe an international filipino scientist in the area of biology so when it comes to taxonomy and my college energy um this is like an uh one of like a leading this is an expert in in the field so who's also based here in the u.s so watch out for that um and then for those of you who may not have attended the first set of webinars on uh research ideation on research on review of literature and also on design of experiment so though all those um video recordings are have have been uploaded on our youtube um channel and this if you would like to check them out and you know participate in our training program so just go to our website um everything is actually there so we're just like we have like a fairly little set of instructions anyways that's five five minutes of fast already all right so we have completed the basic analytical techniques so in our undergraduate chemistry that's uh the basic uh in organic quantitative analysis now we will go to a more sophisticated technique so these are the modern analytical techniques so i guess simone dmv is already here you can take uh uh you can take the stage okay we're back thank you maddie um just like what um marty i'm sorry not maddie uh marty um so the next portion of our webinar is on uh instrumental techniques which is spectroscopy and chromatography um okay so spectroscopy um as you can see um on the animation on the screen just a second um you see you have a wave on the which are 90 degrees of each other so that's called an electromagnetic radiation it has an electric field and a magnetic field component so in spectroscopy that's what um that's what you is involved the uh it's what's involved is the interaction of matter with electronic magnetic electromagnetic radiation so there are different types of emr uh you have radio wave microwave infrared visible light uv x-ray and gamma ray so it's just a simple mnemonic device to remember the um the emr rich men in vancouver use x-ray guns or you can use your own i've just been using this for many years um so in this arrangement you have the emr arranged in decreasing wavelength or increasing frequency or increasing energy so in other words radio wave will have the um the longest wavelength gamma-ray will have the shortest wavelengths and then radio will have the lowest frequency or energy and gamma ray will have the highest frequency or highest energy so in spectroscopy um just like what i mentioned uh the particle interacts with uh with an electromagnetic radiation and when it happens something happens with the particle and it's best described using an energy level diagram oops let me go back so let me go back on the energy diagram you see that if the incoming energy or the emr or electromagnetic radiation um interacts with the particle at ground state if the energy is equal to the energy of transition between electronic states or delta e what happens is the particle gets excited and absorbs that energy sorry absorbs that energy and gets excited so the process that process is called absorption and um the excited state is not very stable so naturally the particle we want to go back to a more stable state or the ground state and in that process the energy that was absorbed theoretically will be released as energy with the same magnitude so that that process is called emission so this is the basic uh principle involved in uh spectroscopy general procedure uh of course you need to prepare your sample then you introduce the sample to the calibrated instrument then the instrument detects the signal from the sample and then signal processing so take note the in spectroscopy you have electrical or optical signal related to the concentration of the analyte some basic components of a spectroscopic instrument are energy source so it's either an amr source well you always have to have an amr source thermal sources and chemical sources you have wavelength selector can be a filter a monochromator or interferometer detectors which can be photon transducers or thermal transducers and then finally you have a signal processor analog meters recorders and computers and normally you have a software that processes the signal that comes from the detector the um sorry so there are many types of spectroscopic techniques as you can see in this table here um but we can actually classify the uh spectroscopic techniques into two uh categories so the first one is when there is an exchange of energy between a photon and a particle photon is just a light particle because i will just briefly say that uh electromagnetic radiation sometimes behave as a particle so it's the wave particle behavior of light so these techniques involve energy change exchange and the type of energy transfer can be absorption emission photoluminescence and chemiluminescence because of time and we will only be talking about uvis and ir spectroscopy these are the common ones that you use for analytical applications so you have uv spectroscopy atomic absorption and infrared and then the other group of spectroscopic techniques is uh where there is no exchange of energy between a photon and the uh sample so the interaction involved uh interactions can be a diffraction refraction scattering and dispersion okay so let's talk about absorption spectroscopy here's a general schematic diagram of absorption spectroscopy so the first uh step is the um uh the emission of your emr from a beam source so that light passes through a sample and um for the most uh for the most part this radiation actually just passes through the uh sample without decreasing in intensity but when the energy or the wavelength is is right if it matches the transition that we talked about earlier energy transition then what happens is the sample absorbs that energy so when that happens the light that comes out of the analyte will uh will be attenuated or reduced so the transmitted light will then be detected by a appropriate detector so generally you you have a transmission spectra when whenever you have an absorption uh spectro spectrometer but um the inverse of that is the absorption spectra which is uh which is what we normally use for calculating the or yeah calculating the concentration of the analyte okay so the first type of absorption spectroscopy that we will be talking about is uh infrared spectroscopy or ir spectroscopy the range is from 780 nanometers to one millimeter so in ir spectroscopy um it exploits the fact that molecules absorb frequencies that are characteristics of their structure so these absorptions occur at what's called resonant frequency so these are the frequencies where the radiation the absorb radiation matches the vibrational frequency so a requirement for um for ir activity is for a vibrational mode to have a change in dipole movement so a permanent dipole is not always necessary this technique is uh commonly used for analyzing samples with covalent bonds so here are just some examples of vibration modes you have symmetric and anti-symmetric stretching scissoring and rocking and wagging and twisting so if the vibration modes upon interaction with the light if the dipole movement is changed then um it is ir active it will show on the ir spectrum so here is just an example of an iris spectra of formaldehyde trained chemists will be able to interpret this peaks and assign each peaks with the type of the uh the bond and the type of the vibrational mode so the ir spectrometer that is commonly used these days is what was called a fourier transform infrared spectrometer or fdir spectrometer so um here's a simple schematic for ftir so remember on the general schematic you shot you let light pass through the sample and then it gets detected on the fdir instrument you have you use what's called an interferometer so what it is uh you have an ir source and then you split it into two at a 90 degree angle and then when they recombine the if the if the phase of the of the light are the same what happens is a constructive interference which creates a more uh amplified light so in other words in this setup your detection will be more sensitive so um what you get is what's called a time domain interferogram and a chemist doesn't really know how to read that so yeah it has to be converted first using a math mathematical transform called fourier transform that's why it's called fourier transform and what we can read is the frequency domain spectra that's what that's what we can use for uh for our purposes yep and just like one one [Music] spectrum so one very important thing that our students should should really have like a fairly deep appreciation of would be uh lewis structures and then the concept of polarity band polarity because these um all have um relationships with the types of signals that you would actually see so for example typically polar bonds they would have some fairly strong responses to ir so that has something to do with um the polarity and the strength of those bonds so it's very important that you're very familiar with lewis structures with bond polarity and also different types of uh functional groups um that would actually respond um to photos 100 agree [Laughter] so here's just more examples of spectra ir spectra sucrose and glycine as you can see i got these from um nisd chemistry web books so um there's actually thousands of spectra available online and you can just download them and then um use these as like your reference spectra especially if you're determining the uh structure of uh of your uh compound or or your uh yeah of your of your compound of interest or your analyte so just like what uh dr bunking said um based on the polar bond polarity and a lewis structure the uh the bands of these uh of these bonds type of bonds will show a different frequency number so here's just the list of main ir spectroscopy spectroscopy bands you will see that on the on the uh left side you have the mo more electro negative or more polar bonds compared to the ones on the on the right side and so on and so forth so ir spectroscopy is normally used for qualitative applications you can use it to identify functional groups and structural elucidation identification of substances because these spectra are unique to that particular substance when you're studying the progress progress of re reaction and when you're detecting impurities so that's it for ir spectroscopy uh let's move on to uh uvis spectroscopy so uv spectroscopy involves um what's called electronic transition and their usual range is from 200 nanometers to 800 nanometers so this energy level diagram just shows you the difference in energy transition between ir and uvis and as you can see ir has a lower energy level transition compared to the uh uvis um transition or yeah electronic transition due to uv vis radiation and that's expected because from our um from our table or diagram of emr ir has lower energy than um than the euvis so in the uvis region um so either you're dealing with molecules or atoms and we will be talking about molecular uv is first um so this requires more advanced uh chemistry here but i'm just going to state it as it is in molecular absorption uh there are allowed um energy transitions yes um so here the the bold ones are the allowed transitions you have the pi to pi star and pi star and sigma uh yeah and to sigma star and what it simply means is your structure should have a pi bond or a double bond or atoms with uh non-bonding orbitals so the bonds and functional groups that have this characteristics are called chromophores so here's just an example of an absorption spectra uh in the uvs region specifically isoprene so in uv spectroscopy um you will encounter what's called beer's law that's not the alcoholic beverage when it's a last name of somebody um so here you see the relationship of absorbance and uh concentration and so absorbance is equal to negative log of the ratio between the incident beam intensity and the transmitted beam intensity and then of course you have the optical path length and the molar absorptivity so this is a constant and then this is based on your uh your instrumental design so from the simple formula you can calculate or correlate the absorbance with the concentration and um normally for uvis measurement you do you construct a calibration first curve first and calibrate your instrument where you have standards and then you measure the respond response absorbance of those particular standards and then use that curve to uh to calculate a solution of a known concentration so here's just a basic instrument design for molecular uv absorption but first let me just show you a um what a spectrophotometer looks like from the outside if you open this compartment you will see a sample holder and a compartment and then the sample holder usually is a cuvette made from quartz material of course there are more advanced uh instrumentation that is available for for uvis spectroscopy so your uv vis instrument could either be a single beam spectrophotometer or a double beam spectrophotometer so single beam um from the name itself you can only uh shine light a single beam through your sample holder and um so you have uh first you have to test the reference which is sometimes normally a blank and then you test the sample so um and then you manually calculate the difference in absorbance on the other hand in wb spectrophotometer you split you split the um the energy source into two and what happens is because of that you simultaneously measure the uh the reference and the sample solution and the difference is read by the difference amplifier and then you get your signal all right so application for molecular uv is i have a long list for environmental analysis um you can use it to to test trace metals uh inorganic non-metals and organics so it's a long list but um you can just i guess uh uh review this uh webinar later on to to review the list and i'm not gonna go over each one of them there's a lot and then another application is for clinical samples so you can also use it to test for um analytes uh in your serum so uh proteins cholesterol uh uric acid serum barbiturates glucose and protein bound iodine so uvis is a lot of applications in in many industries so that's it for the uh molecular uvs the other uh spectroscopy that uses uh uvis is the atomic absorption spectroscopy so like what i mentioned very very early on um in aas the analyte is first atomized before uh detection and there are two common uh types of atomizers so you have the flame atomizer and the electro electrothermal atom atomizer so this diagram just show i mean this slide just shows you a picture of a flame atomizer and we have a simplified drawing drawing of a flame a system so the flame converts your analyte into free atoms and the free atoms interact with the incoming uh universe radiation so the transmitted light is detected just similarly uh just like your molecular use you have a monochromator and then and then detected later on for signal processing and then the other type of atomizer is a electro thermal atomizer so an example is a graphite furnace tube so uh the sample is introduced to a graphite tube which is uh heated viruses resistive heating and with that mechanism you can convert the uh the sample into three atoms and this one you have more sensitivity because your sample is more contained in a graphite too so likewise you have an incident beam bam interacts with their sample and then the light gets filtered and then detected for further signal processing so for aas involved is the uh energy transition of uh of electrons in atoms or ions and these bands are um specific to to your elements so take for example your atomic venture of sodium um these are the wavelengths that corresponds to the uh electro electronic transition so aes is mostly used for analysis of trace metals in a variety of uh matrices and uh for example zinc there here's just a short well it's a long list of uh matrices um or yeah major matrices where you contain zinc and methods have been developed for for the determination of zinc so you could use a s if you want to measure not only zinc but you know trace metals in general if it's in waste water air blood urine and so on and so forth okay so this is actually a bonus topic um because uh mastec is used um also for for uh for trace metal analysis also for um it's being used in tandem with chromatographic techniques which we will be talking about later but in mass spec so you have uh three components you have an ion source a mass analyzer and a detector so what happens is um you can you have an electron beam source or an ionization source that converts your sample into plasma which is the fourth state of matter right or i'm sorry not plasma i'm getting ahead of myself these are ions you convert your uh your sample into ions and then these ions get accelerated to a magnetic field and which is uh this whole system is called a mass analyzer so the ions get accelerated and then subjected to magnetic field that deflects the lightest ions the most so based on this mechanism you can separate the the ions according to their mass and um what the detector reads is the mass to charge ratio of these these ions are fragments so here's a typical mass spectra where you have the mass to charge ratio on the x-axis and then a relative abundance on the y-axis so one type of ionization method is called inductively coupled plasma and this is what i was mentioning earlier where the sample gets converted to uh to into a plasma charge soup of charged particles so uh an icb has typically composed of argon gas and energy is coupled to use it to it using an induction coil to form the plasma so this is at high super high temperature like thousands of celsius and so when the sample interacts with the plasma it becomes plasma itself and um here's just a picture of icp ms so like i said the sample is converted to plasma using your icp before it gets read uh by the by the mass spectrometer so in general icp ms is more sensitive than aas techniques so icpms can be used for the determination of trace metals in drinking water wine food and those down to proteins analysis of soil samples for crime investigations and determination of nutrient levels in agricultural soils so so if you want to select between icp uh and atomic absorption techniques it really depends on your goals uh generally speaking if you want to go um to low very low levels you want to use the icp method specifically icpms because it can read up to ppq levels and if you want to uh if you have many elements if you want to test a solution with many analytes icp is also the way to go however the the downside of icb is guess what the the cost it's more expensive than your traditional aaa so if you don't have icb um you can still use you know your aaa spectroscopy you can um just use whatever you have um and dr dendy there's a number of analytical service laboratories in the philippines so um even universities uh university analytical service lab laboratories such as an up and in latin and in those major universities typically they do have um these types of capabilities that's good that's good to know i think it's just very important for you yeah for you to look to make things apps you don't have to buy you don't have to buy one you just need to know where to look and then um i just have a question i mean like these types of guides you know um um um they're publicly uh accessible right yes they are cool yeah because there might be there might be students and teachers out there who are wondering you know like when do we know when to use um icpms when do we know um when to use um you know your traditional aaa instrument so yeah yeah so i got this information from uh perkin elmer which is a uh manufacturer of icbms so yeah you can just uh type it online um you can just type icp versus aa and you can actually see this uh this particular pdf file okay yeah okay so that's it for uh spectroscopy so um anything else you wanted to add dr jeff i think that's red place it's a fairly well covered um topic yeah just one thing so bindi touched on energy transitions so fundamental because of trigger um quantum numbers your quantum descriptor so you know if you have a fairly good graph of those topics it's going to be fairly straightforward for you to be able to follow or to even understand the principle behind principles behind these analytical instruments yep all right all right yes that's that's very true um yeah um well this is so this is introduction and um yeah i left out a lot of uh of basics yeah yeah it's going to be it's going to be too much for an introductory session and you know those types of discussions would require very focused discussions of quantum essentially physics concepts as well and and you know how they relate to these analytical techniques but then you know i'm i think dr dendi has actually been doing a great job of you know giving you guys an introduction you're like a sneak peek to these types of analytical techniques and instrumentation so i i think you know like this uh this webinar that chief delivered this is uh recorded on our youtube channel so you know if there are things that you need to actually you know after the session you can just like check this out again yep and some some some of the slides that she presented you might actually be able to uh post them on the website so more specifically those reference guides that she shared earlier so you know we can make them available to you yes definitely okay so everyone's still okay um we're on the last leg uh we're talk we will be talking about uh chromatography um so chromatography is a separation uh technique and it's where the molecules are distributed between two phases the two phases are called stationary phase often is a resin and a mobile phase or eluent so the principle behind chromatography is based on the uh strength of intermolecular forces experienced in each phase so basic principle that you need to remember here is are your imfa intermolecular forces of attraction uh like your london forces um dipole-dipole hydrogen bonding and so on and so forth so generally speaking um uh stationary face that's why it's called stationary is because it's not moving it's just stationary um so in chromatography you introduce your um sample the mobile phase is continuously flowing through your uh your stationary face and anything that is has stronger interaction with your stationary face tend to hang out in your in your stationary face longer than the ones that have weaker interactions so in this diagram here the green ones have um are have stronger imfa with the stationary phase compared to the blue one so the blue ones will show first on your chromatogram followed by the uh the green one so they don't stay there forever because you have a mobile phase so you you uh the mobile phase is like your uh carrier solvent uh all throughout the analysis so it's a very the general procedure is very similar to spectroscopy except it involves a sample separation in between into different components so there are many types of chromatographic techniques like your spectroscopic techniques and i will only be covering three of them this morning so uh the first type of uh chromatography is uh is based on the uh chromatographic bed shape so it could be a column chromatography or a planar chromatography so in column chromatography um it's stationed at the stationary bed is within a a glass tube or a plastic tube whereas in planar chromatography the stationary phase is present as or on a plane so like your paper chromatography and thin layer chromatography you can also classify chromatography based on the physical state of the mobile phase so gas chrome or gc mobile phase is a gas and the liquid chromatography is where the mobile phase is a liquid and the final group is based on separation mechanism so you have ion exchange chromatography which separates the analytes based on their respective charges and then size exclusion chromatography which separates the analyze based on their size so let's talk about gas chromatography so it's a it's a technique um for separating and analyzing compounds that can be vaporized without decomposition so um i think the maximum temperature operating temperature for a normal gz is up to 300 degrees celsius so if your sample do not decompose at high temperatures then gc is the way to go so here's a schematic of gc from the name itself our mobile phase is an inert gas uh normally helium and then the helium gets uh filtered before uh it gets introduced into the uh the gc system or into the column and then you have an auto sampler or you can actually manually inject your sample into the injection port where it meets the um the carrier gas so the sample and the mobile phase um travels through the column which is temperature controlled and then the analyte gets detected so just like what i said um on the introduction for jc the analytes are separated based on the their strength of interaction with the column so the column is usually a fused silica or a metal tube where you have a stationary face coated on the inside walls so those that have weakest interaction with the stationary phase in your gc column will get a unit first will get detected first and um and the the one with the strongest will get elite uh last so the the time of uh illusion is uh sometimes referred to as the uh retention time and you will see that on a chromatogram a typical chromatogram so common detectors for gc are flame ionization detector mass spectrometer which we talked about earlier thermal conductivity detector and electron capture detector so for gcf id or flame ionization detector the detector converts your analyte into carbon ions so how does it do that uh it you ignite the detector so you introduce the flame and then you introduce hydrogen gas to form those carbon ions and the carbon ions formed are detected by a cathode collector so on the other hand uh gcms um we already talked about this but same concept the analytes that is being uh are being measured uh get introduced to a mass spec and the the analyte gets converted to into ions normally using electron ionization methods and then the the mass or the ions are sorted out using a mass filter and then gets detected so here is a typical chromatogram generated by a gc um you see like i said you have a retention time on the x-axis and then it's plotted against uh abundance of your analyte and like your um spectroscopy uv spectroscopic techniques um the uh you need a calibration curve uh to quantify the um the analytes in a gc uh analysis and sometimes you also use what's called an internal standard so applications uh here's here's a short list of uh applications uh for for gc technique so you can use it for environmental analysis like uh analysis of greenhouse gases like carbon dioxide methane and knocks in air pesticides and trihalo trihalomethanes and drinking water you can also use it for clinical analysis such as in drugs and blood alcohol analysis forensics consumer products and petroleum and chemical industry and you can also use it for pharmaceutical uh products uh where normally you want to measure the residual solvent of of your manufactured drug substance so that's it for gc let's move on to high performance liquid chromatography or hplc so the concept is similar to gc except that the mobile face is um a liquid in the liquid phase and uh you use a very thin uh column it's it's normally packed in a very thin column the stationary phase that is and uh and because of that you use um you need to uh introduce your or you need to operate the hblc at higher pressure so um you have an hblc pump to pump the mobile phase into into the injector and um the sample is also introduced either you can do it manually but most age abilities these days have auto samplers and then it flows through your hblc for detection and signal processing so the hblc that i'm really familiar with is the ones with from waters i'm not i'm not uh advertising them but this is just what i've used for many many times like hundred times um so if you open this compartment you will see a sample carousel for auto sampling and then these are what you uh what a typical hvlc column look like these bottles are just your solvent uh containers or your mobile phase containers and uh solvents for washing the the system so in an hplc system sometimes you use what's called a guard column to protect your uh your hblc column from uh any contaminants because hblc columns are actually very expensive so um whereas the guard column relatively are cheaper so if you use this as like your filter then you know that the entire technique it becomes more cost efficient so here's an example of an hblc chromatogram uh the mobile phase is usually a mixture of uh water or methanol or you can use acetonitrile or trifluoroacetic acid or more common known as tfa and then and then of course the detection is in the you uh depending on your detector you can you can detect it at the uvs region so likewise uh you can use hplc for quantifying your analytes based on calibration curves so common detectors are your uv detector photodiode arrays and mass spectrometer hblc can be used for uh tracking product purity during pharmaceutical development detection of illegal drugs in urine confirming results of synthesis reactions for research a very specific application is the analysis of vitamin d in plasma for clinical studies determination of floccitine in serum and determination of pah in wastewater so generally speaking if you're if your analyte if your solution is um less volatile hblc is the way to go so like salts inorganics and more complicated structures uh hblc issues usually the way to go not not gc so just one another application is uh analysis of cbd which is a pretty popular these days and um here's just an example of a cbd profile where you want to measure the amount of cbd in your isolate you want to make sure that your thc levels are either non-detect or accept within acceptable limits and of course we know that cbd is the cousin of thc which is found in marijuana so that's it for hplc the final final type of technique that i'll be talking about is science exclusion chromatography dr jeff do you have do you have anything to add before i talk about psychic exclusion yeah it was just just kind of like a an ice breaker for for the benefit of those students so like you know um if you have not really practiced chromatography or if this is the very first time that you've encountered chromatography um you can actually make um you can actually use your friends um for an analogy for for how chromatography works right so then they said earlier that the rate or you know like that like how fast a particular um analyte would um course through the column is down to the detector it depends on the strength of the interaction of your analyte to your your stationary face or your your um your column we don't care those that have shorter retention times those are the ones that don't care they don't stick to those are the ones that typically um show up out of a longer retention time that's her intermolecular forces of attraction so again polarity um um materials with the same polarity would have stronger attractions so if your mobile if your stationary face is polar then all your polar molecules will stick to them but if the situation reverses if you have a non-polar um stationary face all your non-polars would stick more strongly and then you polar these are not really very complicated so yeah and thanks for sharing all these um um dr delhi yeah let me just water will be quite quite quite slow but you know it could also work but and then so um yeah that's an experiment that you can do at home just like you know and then solvents and whether it's water or acetone um anything that you you have at home i'm already realized so i actually had a slide for vapor chrome but i just uh left it out four times yeah we can post those slides on the website yeah yes dr dendy has put legs together you know like a very comprehensive slide deck um for the benefit of those who are interested down yeah so thank you yeah this is a truncated version otherwise we'll be here for another hour yes yeah okay so final final round is the uh size exclusion chromatography so so it's also known as the molecular sieve or gel permeation chromatography or gpc so the separation depends on the ability of the analytes to enter into the force pores of the stationary phase so just here in this diagram here um you will see you will see that solution will contain small molecules and large molecules so the small molecules um can get into the what's called molecular sieves or porous beads so they will stay longer in the stationary phase and the large molecules will just be eluted first and of course you have a mobile phase that that continues to flow through the columns so this type of chromatography is uh the setup is similar to hplc but you're just using different types of columns or columns that contains those molecular sieves so here's just a list of the um the columns that you can use for size exclusion chromatography common detectors include uv-vis detector refractive index and multi-angle light scattering so here the analytes that have higher molecular weight will have a faster retention time and then the ones that have lower molecular weight will have the slower retention time so they will show up on the peaks later on some applications include measuring both the size and polydispersity of a synthesized polymer absolute molecular weight measurements when used in tandem with a viscometer and then you can actually use this to analyze protein structures such as the tertiary and quaternary structure of proteins so to summarize um a technique is any chemical or physical principle that we can use to study an analyte so two broad categories are classical and instrumental gravimetry is a technique that measures mass or change in mass to provide the quantitative information of the analyte in the sample so there were three types of gravumentary covered in this webinar the particular gravimetry volatilization gravimetry and precipitation gravimetry you also have titrometry which is an analytical technique which involves volume as the analytical signal so you have acid base complexiometric and redox statometry we also cover spectroscopy which is due to the interaction of matter and electromagnetic radiation and the most common commonly used techniques involve absorption of energy so we covered ir spectroscopy uv spectroscopy and atomic absorption spectroscopy chromatography is a separation technique due to intermolecular forces of attraction differences between the stationary phase and the mobile phase the common techniques are gas chromatography hblc and size exclusion chromatography and finally we notice that analytical techniques are quite useful in several industries such as environmental food pharmaceutical research petrochemical forensic science clinical studies etc etc so my main reference for this webinar is listed on the screen it's a free ebook by dr harvey and that's it so i guess we can now open to q a uh thank you mom dindy uh can we give her a virtual clap here in zoom and also in youtube sombra tagalon that's around two hours so this is a very good uh introduction to analytical techniques conventional and modern analytical techniques that you can use actually especially when you will take the board exam so if you if you want to refresh your memory about analytical techniques this is a very good lecture for that so we have a lot of questions but for the speaker's information our viewers are well represented so we have some uh someone from the north maine from mmsu that's region where i know marco state university we have uh a class from visayas eastern visayas state university from tacloban and merundin is a class from ndmu notre dame of marbella university in coronado city so thank you for is in our webinar so we have a lot of questions in youtube uh also if you want to ask live questions here in zoom you can press the raise your hand button so i'll start with the questions in youtube mamdindi can you expand on the concept of equivalence point versus end point and how a proper choice of chemical and indicator can be made so interchangeable means can you give us uh you uh expand on the concept of this two uh two uh so equivalence point is you know i know stoichiometric ratio so it's based on your uh balanced chemical equation just like what dr bunking said so it's a it's a theoretically determined whereas the endpoint um is based on normally um you use those indicators that change uh uh the change colors or um yeah the change colors upon chemical reactions so um so normally the during titration the ph changes right so um because of that ph change the indicator color also changes and each color each indicator has specific ph range so for example um let's see let me go back to can am i still sharing my screen yeah yeah okay so let's let's go back to that table of um of indicators yeah i i think that's actually like a very nice question because it's very important that um you guys have a very good understanding i think my um but i'm hoping you can still hear me um it's very important that you that you have a good understanding of these two different terms because you know equivalence point is different from endpoints yeah because like endpoints it's just it's related to your indicator as the nps actually said so if you pick the wrong indicator for a titration experiment you might see um a change in the color before you reach the equivalent point so you're going to get a wrong measurement measurement that's right and there could also be times when say if your indicator changes at a large excess of your titrand sometimes you would see the change in color will you pass the equivalence point that's right so you have to make sure that the equivalence point happens within the working range of your indicator so for example sodium hydroxide hydrochloric acid so the product of uh that acid-base reaction is just water which is neutral and sodium chloride which is a neutral salt as well so that but you would expect that at the equivalence point enough you amount to hydrochloric acid and the amount of the sodium hydroxide if that's equal that's your equivalence point you would expect a ph of seven for that solution so you should fit an indicator that would change color within the you live in a ph range that covers seven so then yeah so i actually have had a slide of different indicators at different titration curves that i omitted but it will be available so so the titration curve actually can also be useful so for example a strong acid strong base um you see the equivalence point region is from ph let's say 4 to 10. so normally you would um you would select the indicator that is within this uh this sharp the sharp change in ph right here so you could also so phenolphthalein is the common but you can also use a methyl orange for this type of titration and it's upon information at all when it comes to indicators these are all available online these are very these are searchable information so in case you know you have you're having second thoughts if you're using the right indicator google google just google all these they'll find the answer yeah you can send those questions you just you're mostly chemistry yeah you just need to know your working ph on the utilization side or on the equivalence point appropriate nah yeah and i said marty i think yeah i think i saw i saw a question earlier that's related to you know like ph my mom is calling i'm gonna have to use it um it's not at neutral back at no basic or back of our high school and college students so um there are times that when you're doing asset based situations that the end point is say on in on a basic uh ph range so sometimes nine sometimes then and that typically happens when you are um titrating weak acids and bases so for example you have acetic acid and you're titrating it say with a strong base um say sodium hydroxide for example the product of that titration um so acetic acid and sodium hydroxide you would form water and sodium acetate so now the question is when a weak acid reacts and undergoes acid-base reaction the product of that is also a weak base so what happens is your weak base which is your acetate ion when that associates in in in water in an aqueous environment that will react with water so it will abstract a person from water and generate a hydroxide ion so the accumulation of those hydroxide ions from the um weak a conjugate base that forms that's causing the ph to go high so if you're if you're so if you're titrating strong acids with strong bases you will get a neutral ph for the solution but if you are if one of your components is either a weak acid or a weak base um then you will have a non-neutral ph so it's very important that you also know the strength of the strengths of your acids and the products that they form so yeah the concept of weak acids and conjugate bases and weak bases and conjugate acids that's something that you have to be able to to be familiar with and also the concepts of chemical equilibrium because you know um unless you're using as a strong acid and base um reactant pair then you know you will always have to deal with these dissociation um in aqueous phase of your conjugate acids and bases so that's nice to watch yes that's all right yeah we missed uh defining a weak acid base or a strong acid in base so that's a very good explanation yeah yeah i mean i mean like our intention for some of these webinars so i mean again these are the this is an overview you know this is an overview of analytical techniques and and um instrumental um analysis techniques that are out there so you know like hopefully later on if we can like invite dr back we can have focus discussions on certain topics very generous and passionate to actually help out and you know um marty you mentioned that you know there are some students from mariano marcos university and other universities actually the idea of this webinar just came about like sometime last week right dindy just like give you guys a background webinar so some of those students from mariana marcus university who happen to be the students of a very good friend of mine who studied here in in houston uh they were checking out like some webinars but um you know there's a fee and you know like obviously you know like times are tough right now so you know like we i felt bad when when my friend mentioned to me that yeah they wanted to attend that um webinar but you know it's about like a thousand so i prefer for the registrations i was like okay perhaps i can tap into like some of my friends who are generous enough to share like their expertise and time so i reached out to dindy and it was like an immediate yes she came up with the 131 slide presentation for all of you guys um hopefully enjoys this experience and like um we have like a bunch of very good friend uh friends um you know like in in the stem area and you know you'll see all these faces you know like getting involved in our endeavor so thank you so much lindy this is really i mean you're welcome questions but you know i cannot i cannot you know i i i i always have to express you know the gratitude because this is actually for those students yes definitely yeah yes we have a lot of bs chemistry students and chemical engineering students that are uh saying hi in uh the youtube uh youtube comment box so there are a lot of us one of the main missions of films i have um you know um there's a bunch of us um who fortunately have been you know blessed with fairly good career opportunities abroad and we were trained in the philippines this is our only way of you know paying it forward but unfortunately we ended up like getting settled here in the us but you know like we all have we have we now have all these platforms that enable for us to share everything that we have learned you know from from our years of experience um um in in the sciences please reach out to us for send us messages if there are like some topics that would help you mm-hmm um and and your understanding of science is not only for in chemistry um we can we will try to find helpful so we just need your engagement um send us your feedback and request and we i mean whenever and wherever possible we'll try to do we'll try to help you out all right so let's that's that's that that's the goal and that's the vision of yes i have and now uh we will be going back to the airport yes or abroad lots of questions absolutely how much dopo in wheat will be the minimum amount i think this is of the sample for instance is required if you want to test for volatilization gravimetry so an adopted limit of detection or sensitivity i know i think he's just asking or that person is just asking about the amount so depending on the monograph a so specific uh compounds have what's called a monograph usually it's around two grams of sample that you need for uh for loss on drying question earlier so okay all right so yeah very specific for the monograph for the particular substance clarification color change or recognition seems to be subjective or qualitative what can we do to observe quantitative information aside from ph can we use or add spectroscopy to the setup definitely you can you can but it's not necessary you can only just yeah go ahead jeff so if you if you guys have learned in um how to do that symmetry the right way and by that i mean you have your standardization of your solutions you're confident with the concentration of your titrant you have very good weighing um skills you have very good record keeping skills um you know the subjectivity of it you know it comes with practice for so you know like the more you do the titration um the more sensitive you'll be when it comes to you know figuring figuring out when am i nearing the equivalence point you know there's there's some some kind of chemical intuition that gets developed as you practice this more and more so you know quite unfortunately in in the classroom setting um a student we don't have to do this you know once or twice per semester so it's very difficult to get them trained so um but i mean most if you're a chemistry major um i mean you can um have your practical like in an analytical lab for you to be able to get exposed to more of these but yeah more than anything for more than the conceptual um um framework around it you know practice poisoning the practice makes perfect practice will make you an expert like uh at carrying out like all these um experiments and you know um spectroscopy would actually be quite ideal you know like by all means if you have um uh that capability you know you can you can compliment um you can use it as a complimentary technique to say confirm you know like the progress of a particular reaction whether it be your titrating or you know whether you're you're inducing a precipitation but yeah i mean um titrometry is a fairly reliable um technique if you um are if you have actually become like quite experienced um at it so yeah do you have something do you have something to add mumbi no um well titration requires a lot of patience well and i mean initially you can uh determine the equivalence point by calculations device so when you're close to that volume then that's where you can uh gradually slowly add your titrand and like what jeff said it takes a lot of practice um parama develop your uh your titration technique so and then you know what's very important thing for there's a concept of back titration that's right yeah and um so you subtitle again if you know your your balance if you have your balanced chemical equation if you understand the chemical reaction involved there are ways to go around you know um mishaps or your imagination they go unsaturated [Laughter] yeah i mean i was when i was taking up chem 32 i mean i i mean i i got i got i i got a higher mark for analytical chemistry but that doesn't mean that i did all my titrations i just understood the chemical reaction you hit it you're good that's why uh yeah that's why we sometimes extend the lab it was six hours yawn so means i'm telling them i'll be coming in six hours yeah you will not be a successful analytical chemist if you don't know how to block by trade ultimate test of patience because that's right if you can put you can put like a half drop you know sometimes a half drop in excess is enough to kind of like mess it up let's just let's just put it into perspective [Music] some level of error in in your measurement i mean again whenever you're performing analytical measurements it's very important to run replicates you don't only do it once and report your data so you know like uh an effective um analytical chemist would do things at least three times if you're running all these moments that's right my second chance thanks marty for that and no clarification intensity titration and you have uh patience and the practice then you can actually perfect the uh the technique and and you know what sometimes okay this is also like one particular brute force technique that we do if you have enough of the reagents and of your samples sometimes put the first attempt it fails because you're just trying to get an idea of okay it has changed already then on your second trial you know when once you're at your 23rd ml you can do it like more slowly because before we let go of monday [Laughter] is it appropriate to use gcms to determine the concentration of pesticide dressing juice in food products or crops yes so normal uh yeah you can um so there's uh uh they're called they are considered semi-volatile but uh uh so you could still use gcms for that yeah can you use gc alone um well you have to have a detector [Laughter] so normally uh for for pesticides yeah gcms is a tandem for uh uh for detection you can use your ucf id or gct yeah as long as you don't have understand their standards yeah okay uh a good depo uh thank you for this tour just wanna ask if you could recommend a good software for spectroscopy like spectral analysis that's very broad yeah msk if you have a detector means and uh it comes with the song yeah yeah normally it comes to the software now so well i i can't really recommend anything that's a very wrong question yeah yeah it depends on the on the equipment that's right and there are there are uh established libraries especially for mass spec uh data so you you just need to uh access those libraries that's right do you have any uh perspective spectral analysis um so marty there's a question here and you might be able to answer this because you're in the philippines so um is there any future in the philippines that offers training for analytical techniques so by the way martipo is a head of is the head of an analytical service [Laughter] if it's a specialized uh method like say for example you're detecting some secondary metabolites it's a specialized uh training so in a request among analytical services laboratory or pediatric fnri and other government agencies equipment so it depends actually you need to arrange the training and if the training some size is at least ten that would be a go so you need an initial communication first with the public club or me bettering private laboratories analytical laboratories are private so you just need to communicate with them first because if you want to have a specialized training adept is a basic technique so we we want to be trained doing some specialized techniques and other agencies input because we specialized on crops can i ask mom if the temperature if the temperature of a solution has the ability to alter the luminous intensity emitted and how it will affect the luminescence but um well it depends on your uh your instrumentation i mean if you're so gonna ignite it or subject it to high temperature then the temperature of the solution doesn't if he if the person's asking about just the solution the temperature of the solution before you introduce it to the instrument um so but uh if it's a uh it's at the lower temperature um normally temperature just uh increases the um the flow rate so uh that's how it will affect the uh the the analysis so again if that person is asking about a sample prep right um for consideration so depending on you know so that's gonna cause a problem because you you're not sure that your the entirety of your analyte is is within your liquid matrix so things to watch out purple um um another thing if you're dealing with thermally sensitive or yeah thermally sensitive materials then definitely you have to you have to watch out for that you know like the temperature of your of your of your sample matrix has to be able to um you know factor that in but then again so there's there's a lot there's a lot a lot of things to watch out all right so i think we will cut the discussion there because it's already 12 30 and uh it's almost lunch time for our participants so uh again we would like to thank dr dindy voyles for her generous time and expertise and sharing with us uh all this knowledge that she has in analytical chemistry so thank you poor mom again it's good you're welcome thank you do you have any message to the people who are watching especially to the students and to the teachers yeah um so i guess for students i don't know madame resources online so grab grab those resources um and like before in during my time back in the day um library library library library you know you have resources at your uh fingertips so utilize those and um um yeah analytical chemistry and uh there are many applications so if you choose this if you chose this career path like if you want to be an analytical chemist i assure you that like uh because there's always a need for uh for analytical chemists in in many many industries so that's my encouragement to you guys and uh for teachers uh likewise you know marami dying resources online um uh you can use those resources for more uh you know to to increase your creativity with teaching and also um ways of of teaching methods if you're teaching titration to your students [Laughter] speaking but there are online resources that you can use to simulate titration the students can um go on i i i i don't have the specific web websites but there are websites out there where the students can virtually do the titration themselves for them to experience it resources out there so as did actually mentioned um you just have to be quite patient and you have to scan your environment there are a free resources out there that you can use um for this i mean like for now i mean like after this the lecture that dendi delivered it's gonna be immortalized um on the worldwide moralized no because it's all the good and bad thing you can you can use that you can revisit the toy you know um if you wanna i'm for a refresher of course i have to say it's been age just since i i you know i i heard discussions about the other types of chromatography i know spectroscopic techniques so like i mean for someone like me um who have not really been practicing analytical technique much um over the past years then you know this is a very good refresher um for me so thank you so much lindy you're welcome and all this support feels like um activities here so uh just stay stay tuned thank you thank you so much uh jeff can you share your scream for the announcement uh by the way the evaluation forms are already posted in the zoom chat box and also in the youtube comment section so if uh just fill out the form and we will be giving you your e-certificate so before we end this uh we end this uh webinar we would like to invite you to our next webinar that will be happening two weeks from now so we at jeff will discuss with me a sec yeah yeah but you will discuss about this at this webinar so again see mundane depot is a very thankful kamikaze dedication imagine in newport one hundred thirty one yeah when i mentioned today that there are students who really wanted to um attend um um um a virtual analytical um chemistry webinar um for a fee um you know um you know it touched her heart and yeah she um volunteered yes immediately to our to our request for for this lecture yeah okay so yeah thank you for staying up till midnight because uh past that time napoleon [Laughter] [Music] uh two weeks from now um research proposal writing so then and workshop at the same time so we highly encourage um all the teachers and students out there to participate um um in this event and then yeah we're gonna be launching uh phil scihop's lions virtual competition for the best um science investigatory project ideas to present to our panel of of judges so things to watch out for and then um as we mentioned um a month from from that date uh marty will be delivery sharing some ideas on research topics that you can investigate at the comforts of your home or within your community uh laboratory resources so um um sense of creativity [Music] brainstorming exercise so how do you manage a large set of ideas and how can you actually identify um the single most um promising idea so finally prioritizing ideas nino if you're working on on on research ideation as a group and then in the march month of march webinars so keep checking um out for announcements as i'm in phone website triple w fuzzy hub.com and then sami official facebook page and then we also post our video announcements and teasers for me youtube channel so um subscribe um and then yeah that way um you'll know if we have like some new contents released um i'm quite um often every every every every quite often so yeah i mean um it's it's already posted in the youtube chat box and also on on the zoom chat box so and then um uh google for important what's the website so you can check check check that out um for you to get your certificate of participation and doctor hopefully this is the start of you know hopefully um you know more in the future you know like whenever your time permits um it's it's really a great pleasure and we're we're really blessed by by the wisdom and you know and all these materials that you uh thoughtfully prepared for for the filipino we were having panic attacks like earlier because we thought that we're going to be losing the live stream so good thing if that didn't happen but i mean what happens and then um we're just going to have like a deep briefing amongst the four of us like after the session we'll send you a separate google zoom link zoom session information thank you so much everyone especially to those who stayed with us we have a total of around around 650 at max viewers during the peak of the discussion for staying with us and stay tuned for more offerings of fields i have you can follow us on facebook filipino science um youtube vince i have and our website fieldsidehub.com so with that have a happy lunch everyone and have enjoy your weekend everyone mom didn't be we will have that dinner yeah thank you paul and week you

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Length: 164min 30sec (9870 seconds)

Published: Fri Feb 05 2021