Y khoa, dược - Micropipette tutorial from the office of science lab technical assistant ccc

200-10002 7 8Micropipette TutorialFrom the Office ofScience Lab Technical AssistantCCC200-1000 μL2 7 8This is a Micropipette it is used to accurately transfer small quantities of liquid. On this model the desired volume can be adjusted within the range of microliters (μL). 200 μLSome Micropipettes have preset volumes and cannot be adjusted.This pipette will only deliver 200μL.How does it work?It works much like a syringe that would deliver an injection. Inside there is a spring loaded piston that moves up and down. 2 7 8The plunger has two stops: - at the First Stop the piston moves through the volume that is set on the pipette. (In this case 278μL)2 7 82 7 8278μL- The second stop is extra travel used for certain circumstances like evacuating the tip, or drawing up more than the volume indicated on the pipette 2 7 82 7 8278μL- Extra volume (? μL)- Find all three positions. 2 7 82 7 82 7 8Proper Use RULE OF THUMB: Always select the SMALLEST size pipet that will handle the volume you wish to move to achieve the greatest accuracy. Accuracy decreases as you use unnecessarily large pipets for small volumes.P20 pipet: Maximum volume 20ul. Accurate between 2ul and 20ul P100 pipet: Maximum volume 100ul. Accurate between 10ul and 100ul.  Deliver 15ul  which pipet?200-10002 7 8Set the correct volume on your micropipette by turning the adjustment knob (typically the plunger button) clockwise to increase volume orcounterclockwise to decrease volumeThis pipette’s range is 200-1000 μL and is set to deliver 278μLSetting Volume 2 7 8NEVER exceed the upper or lower limits of the pipette.20-1002 7 8Settings can vary between models and manufacturer s.This pipette’s range is 20-100 μL and is set to deliver 27.8μLHowever you might see the following readings for this exact setting on different pipettes:Setting Volume 2 7 82 7 . 8 2 7 8The first two make the decimal places obvious, while the last one implies the tenths place if you know the range.1.00-10.00 2 7 8Settings can vary between models and manufacturer s.This pipette’s range is 1-10 μL and is set to deliver 2.78μLHowever you might see the following readings for this exact setting on different pipettes:Setting Volume 2 7 82 .7 8 2 7 8Attaching tipBe sure to choose the proper size tip. 2 7 8Attaching tipPress the pipette into the tip firmly to create an airtight seal. 2 7 8Attaining a SampleSTEP ONE – press plunger to first stop and hold.HOLD2 7 8Attaining a SampleSTEP TWO – Insert tip into sample only far enough to ensure it stays submerged but not to the bottom where it will get blockedHOLDKEEP the pipette VERTICAL at all times2 7 8Attaining a SampleSTEP THREE – Allow plunger to return to the home position SLOWLY so you don’t draw in air bubbles, or splash sample up into tip or the pipette itself.KEEP the pipette VERTICAL at all timesAttaining a SampleRemoved tip from sample before the plunger was all the way homeLikely allowed the plunger to move to home too quickly. CORRECT2 7 8Delivering the SampleSTEP FOUR – insert tip into the area you wish to deliver your sample. (in this case a gel) KEEP the pipette VERTICAL at all times2 7 8Delivering the SampleSTEP FIVE – depress the plunger slowly to the first stop, then continue to the second stop, this will evacuate the entire contents of the tip. And HOLDHOLDKEEP the pipette VERTICAL at all times2 7 8Delivering the SampleSTEP SIX – While still holding the plunger at the second stop. Withdraw the tip from the well. HOLDKEEP the pipette VERTICAL at all times2 7 8Delivering the SampleSTEP SEVEN – Allow the plunger to return home.KEEP the pipette VERTICAL at all times2 7 8Discarding the TipSTEP EIGHT – Place tip into the opening of the waste container, then depress the tip ejector. WASTETip EjectorBe sure to use a new tip each time. KEEP the pipette VERTICAL at all timesThings to AVOID !!278Never use a pipette in anything but a vertical orientation.Things to AVOID !!278Never use a pipette without a tip.Small Volumes TechniqueWith small volumes, especially the 1-10ul range, you must keep track of the droplets you pipet.Carefully expel the liquid droplet on the side wall of the tube so that you can see it, drawing the tip away/out carefully BEFORE releasing the plunger.If adding to a larger volume, flush the tip with the solvent liquid after expelling the droplet to make sure you get all the delivery liquid. Reverse pipetting vs. forward pipettingReverse pipetting is recommended for solutions with a high viscosity or a tendency to foamPress the plunger to the second stop.Dip the tip into the solution, and slowly release the plunger  fill the tip with a volume that is larger than the set volume.Dispense the liquid into the receiving vessel by pressing the plunger to the first stop  this volume is equal to the set volume. Hold the button in this position.The liquid remaining in the tip can be pipetted back into the original solution or disposed together with the tip.Release the plunger to the ready position.Pipetting volatile compoundsTechnique: use the forward pipetting technique.1-2: Calibrate the pipette with the volatile compound  aspirate and dispense the liquid a few times keeping the tip in the liquid. By doing so, the air inside the pipette will be saturated with vapor of the volatile compound. 3-6: Pipette rapidly to avoid evaporation using the forward pipetting technique.