Basic Lab Skills Training

hello the purpose of this video is to train new students how to use some of the basic equipment that you'll be using in the lab for example if you ever need to transfer liquid volumes you probably use a pipetter also known as a pipet pipets come in a range of sizes and can accurately transport volumes as small as 0.2 or as large as 1,000 microl the volume range of each pipet is shown on top of its plunger for example this P20 pipet can transfer 2 to 20 microl sometimes only the maximum volume of the pipet is shown on the plunger but the volume range of all pipets is 10-fold so this pipet transfers 10 to 100 microl to change the volume setting on a pipet rotate the black knob near the top as shown here note that since this is a p1000 pipet one of the digits is shown in red to indicate milliliters the other two digits are shown in Black for microliters right now the PIP is set to 1 ml on a P20 pipet one of the digits is red to represent nanoliters while the other two digits are shown in Black for microliters in this example the PIP head is set to 18.7 microl on a P2 pipet two of the digits are shown in red and one is in Black for microliters in this example the pipet is currently set to 1.32 microl just as pipets have unique volume ranges they also require unique tips for example this p1000 requires large Blue tips always make sure that the tips fit on snugly if the tips fit On Loosely or fall off then they won't work properly and you'll need to find some other tips pipets use a two-stop plunger system to transfer liquids the first stop as shown here is used to draw up the liquid the second stop is used to completely eject the liquid from the tip so once again the first stop is used to draw up Liquid while the second stop is used to eject it when transferring a sample Begin by pushing the plunger down to the first stop to eject all of the air then submerge the tip and release the plunger as you eject the sample push all the way to the second stop to make sure that all the liquid leaves the tip when you are done using the tip eject it into a Sharps box using the ejector Button as shown here if your pipet does not have a working ejector button you can always take off the tip manually by hand if you ever think a pipet is inaccurate you can test it using an analytical balance in this example we're going to test a p1000 pipet by setting it to 700 micr since the density of water is 1 G per ml 700 micr of water should weigh 700 mg Begin by tearing a way booat and then slowly transferring the liquid volume to the way booat make sure you completely eject all of the liquid then close the doors on the analytical balance and wait for the reading to stabilize in this case the reading is only 541 mg which is much less than the expected 700 mg therefore the pipet is in dire need of calibration you should no longer use the pipet for any experiments and immediately let your supervisor know that the pipet needs to be calibrated if you need to transfer volumes larger than 1 ml you'll need to use a pipet Aid pipet AIDS use much larger tips with volume ranges from 2 to 50 ml Begin by tightly inserting the tip into the pipet a then submerge the tip into the liquid draw liquid up with the top button and eject liquid with the bottom button if at any point you draw liquid too far up the pipet will stop working this is because all pipet AIDS use an air filter to protect themselves from liquid contamination therefore to get the pipet eight working again you have to disassemble the PIP head head and remove the clogged filter as shown here once you've removed the Clogg filter you'll need to replace it with a new filter note that syringe filters designed for liquid will not work properly in a pipet 8 you must use the a air filter specifically designed for your pipet a once you have removed the old clogged filter and thoroughly dried all the plastic pieces reassemble the pipe pade making sure that the new filter and all the rubber pieces are in the correct orientation once you put it back together test it with some liquid to make sure that it works if the PIP pad Aid continues to malfunction let your supervisor know immediately in addition to transferring liquid volumes you also have to weigh out a variety of chemicals in your research to do so we use balances most Labs have two types of balances a crude balance for large masses and an analytical balance for very small masses it is very important that you only weigh large masses on the crude balance and small masses on the analytical balance this is because large masses will actually break the analytical balance while the crude balance is not accurate enough to precisely weigh small masses to weigh masses larger than 1 G use a way booat insert the way booat into the analytical balance close all the doors and tear it to set the mass to zero then add your chemical to weigh masses smaller than a gram use a weighing paper weighing papers are preferred because they cling less to small powders and crystals transfer your chemical to the way paper using a clean spatula or cupula as shown here slowly add the chemical to the way paper to prevent going over the desired weight check the exact weight by closing the doors on the analytical balance and giving it a few seconds to stabilize as long as your spatula is clean you may return any excess chemical to the original bottle that came from if you are ever weighing out a chemical and you accidentally spill some of it on the balance or bench you'll need to clean it up immediately Begin by removing your weight out chemical from the balance then use a brush to clean up any spil powder or crystals once you have it all cleaned up make sure you properly dispose of the chemical just like a pipetter an analytical balance can also become inaccurate over time to test the accuracy of an analytical balance you'll need two standardized weights at the upper and lower bounds of the balance in this case we're using two and 50 g weights notice that the 2 G weight is reading 1. n98 G Which is less than 1% inaccurate so that's pretty good next we test the 50 g weight which weighs out to be 49.95 G this is also greater than 99.9% accurate so the balance is working properly if these readings were significantly off we would need to calibrate the balance refer the manufacturers instru instructions on how to do so or let your supervisor know immediately so just a review use crude balances for large weights which is typically anything over about 5 G use analytical balances for any small weights anything from .1 mgram all the way up to a gram and please clean off the balances and the bench if you spill any chemicals centrifuges are also commonly found in most Labs they're used to sep at particles of different densities by spinning them rapidly to generate a high G Force since most centrifuges do operate at rather high speeds it is important that you know how to properly use them to avoid damaging the centrifuge or harming yourself the most important thing you need to know about using a centrifuge is that any samples you put on the rotor must be properly balanced use an analytical balance to make sure the weights of your samples are equivalent and adjust them as necessary if you ever have an odd number of samples you can always use a tube of water to even things out when putting your samples on the rotor make sure they're exactly opposite one another otherwise you get an imbalance error next put a lid on the rotor just in case any of your samples leak out to set the speed on the centrifuge always begin by selecting either gForce or RPM for revolutions per minute note that gForce may also be shown as RCF for relative centrifugal force next set the time on the centrifuge and start the run you should you should always stick around to watch the centrifuge reach maximum speed just in case there's any kind of imbalance error once the centrifuge has finished wait for the rotor to completely stop spinning then remove your samples you should always check your samples to make sure the desired sedimentation has occurred when you're done with the cuge put the rotor lid back in place and close the main lid whenever you're using larger centrifuges that use buckets or 50 ml tubes is important that you only fill them up to about 80% of their maximum value for instance here we're only filling up the 50 ml tube to 40 ml this is because tubes and buckets do not have perfect seals therefore when they're spun at high speeds they can leak out if they're overfilled so to prevent making a huge mess that you have to clean up in the centrifuge only fill up 50 ml tubes to 40 ML and fill 600 mL buckets to around 400 ml so just a review when using a centrifuge always make sure that your samples are properly balanced and finally when using 50 ml tubes or large buckets only fill them to 80% of their maximum volume to prevent any spills that might happen in the centrifuge if a spill does occur make sure that you clean it up immediately the most important thing you need to know about a pH meter is that the electrode must be stored in electrode storage solution in between uses if the electrode storage solution runs dry then the pH meter will stop working properly and the electrode may even break if you ever notice that the storage solution is run dry immediately fill it back up with fresh electrode storage solution several companies offer pre-made Storage Solutions or you can make your own by mixing 100 migam of potassium chloride with 10 MLS of the ph4 standard solution when you are ready to use the electrode remove it from the storage solution and thoroughly dry it with a chem wipe next rinse off the electrode with milq water and dry it again to calibrate the meter pour a little bit of the standard solution into a 15 ml2 this prevents the main standard solution from becoming contaminated you can refer to to the manufacturer's instructions for specific protocols on how to calibrate your pH meter however in general pH standard Solutions of 4 7 and 10 are usually used to calibrate pH meters when calibrating the meter it is important that you use the two standard solutions that are closest to the pH of your buffer for example if you plan on making a sample with a pH of six you want to calibrate with the four and seven standards however if the pH of your buffer will will be 8.5 then you want to calibrate the meter with the pH 7 and 10 standard solutions to measure PH completely submerge the tip of the electrode Into Your solution and ensure that it is vigorously mixed the best way to do this is use a stirbar in a stir plate but you can do it with your hand if those are unavailable remember to press the read button on the pH meter and give it a little while to stabilize once the reading has stabilized you can adjust the pH of the solution with hydrochloric acid or sodium hydroxide note that hydrochloric acid will decrease the pH while sodium hydroxide will raise the pH in either case add the acid or base in small amounts and vigorously mix the solution after you add them it is important that you add the acid and base in very small amounts such that you don't overshoot and have to add excess acid and base this will prevent you from adding too much salt to your solution once you are done titrating your solution remember to put the electrode back into the storage solution I'd like to stop for a moment to talk specifically about buffers the purpose of a buffer is to maintain the pH of a solution even though a reaction may be occurring that would otherwise raise or lower the ph the most important thing you need to know about buffers is that they are only effective within specific pH ranges for example Biz Tris buffer is only effective between pH 5.8 and 7.3 therefore if you titrate it to ph8 it will not resist pH change effectively instead if you need to make a buffer at ph8 it would be better to use Tris HCL which has a range from 7.2 to 9 it is important to mention that the buffer should in this table are only a small sampling of all the buffers available you can find many more online which may be useful for your experiments aside from the PH range of a buffer you should also consider its chemical reactivity for example Tris buffers are weak key laters that means they will weakly bind metal ions in addition heaps buffers generate free radicals that can significantly interfere with your chemical reaction if exposed to sunlight therefore you should always remember to check the PH range and the reactivity of your buffer just to make sure it's ideal for the reaction that you're trying to do if you work with any hazardous chemicals in your research you'll probably need to use the fume Hood at some point to begin working in the fume Hood raise the sash to the maximum safe height note that if you raise it too high the fume Hood will not work properly and some Vapors May Escape into the lap when you raise the sash it should start drawing air inwards if there is no air flow or any alarms go off in the hood you should let your supervisor know immediately and not use the fume Hood when performing experiments in the fume Hood you should always work at least 6 in deep this will prevent any Vapors from accidentally escaping from the fume Hood in addition you should always keep the fume Hood as clean and empty as possible this will prevent hazardous chemicals from crossreacting from one another and it will ensure that the vent that you can see in the back of the fum hood here will remain unblocked and working properly remember if these vents become blocked the fume Hood may lose suction and hazardous Vapors May Escape into the lab so to review before working in the fum Hood always check the air flow of the hood you should also work 6 in deep at all times and try not to block any of the vents inside of the fum Hood another commonly used piece of equipment in all of our Labs is the ultrapure water system ultrapure water should be used for all of your buffers since tap water and even distilled water may have some contaminants that could interfere with your reactions to collect Ultra Pure Water Place the dispensing hose inside your bottle and pull the trigger as shown here do not let bottles fill up on the bench instead put them in the sink just in case you forget about them and they overflow please note that if you do you leave a bottle on the bench and it overflows it can flood the lab thereby damaging or ruining many expensive pieces of lab equipment when collecting Ultra Pure Water you should always check the readout on the system to ensure that the water is Ultra Pure Ultra Pure Water has a resistivity of 18.2 megaohms per centimeter as shown on the readout here if the resistivity is any lower that means your water is not Ultra Pure and one of the filters in the system will likely need to be replaced notify your supervisor if this is the case also notify your supervisor If You observe any alarms on the system once you have your Ultra Pure Water you probably use a stir plate to make your solution Begin by inserting a stir bar that isn't too big or too small for the bottle then slowly turn up the RPMs and add your chemical that you wish to dissolve in some cases You may wish to heat the sample as well please remember to use Extreme Caution when heating liquids on a hot plate for example do not heat water above its boiling point which can be 90 to 100° C unless you are explicitly trying to boil it volatile solvents should only be heated in the chemical fum Hood to avoid inhalation of any harmful Vapors finally hot plates should not be left on at high temperatures for extended periods of time for for example try not to leave a hot plate on overnight since it is not uncommon for hot plates to overheat and create a fire hazard when left unattended so that's the end of this video I hope it's been useful please contact your adviser if you have any more questions on any of these pieces of equipment

Channel: Jacob Elmer

Views: 174,222

Keywords:

Id: Nqj41O8FH5c

Length: 18min 18sec (1098 seconds)

Published: Fri Aug 29 2014