A micropipettor is an instrument used to accurately measure liquid
volumes. We will use Rainin
micropipettors for volumes at or below 5 mL, usually in the microliter (μL, 10-6 L) range. Pipettors are
accurate devices. A p1000 can
measure 1 mL volume to a precision of 1.3 μL.
To set pipetting volume:
- Twist the volume lock
to loosen (1/8th turn)
- Twist the plunger
button clockwise or counter-clockwise until the numbers read the proper
volume. Note: In between the
bottom numbers are four ticks which represent 0.2 divisions.
- Lock the volume lock
To transfer liquid:
The plunger button may be depressed at two different stops. The first is an accurate measure of the
total volume. The second (100%
depressed) is a “blow out”.
- Put a tip on the
pipettor shaft by gently, firmly inserting the shaft into a tip held in
- Depress the plunger
button to the FIRST STOP.
- Immerse the tip into
your liquid a few mm’s and release the plunger slowly.
- Dispense the liquid
into its designated container slowly by pressing the plunger to the
first stop again.
- Remove the tip from the
liquid and completely press the plunger to the SECOND stop to blow out the
- Eject the tip with the
white button below the volume lock ring into a beaker or other container
designated for tip disposal.
- ALWAYS PUT ON TIPS BEFORE SUCKING UP YOUR SOLUTION PIPETTE VERTICALLY, DO NOT TILT THE PIPETTOR, NEVER TURN THE PIPETTE UPSIDE DOWN. (This lets liquid into the pipette shaft, which ruins it.)
- Never try to pipette solutions beyond the limit
volume (minimum is 10% of the maximum).
- It is important to use the right sized tips for
the pipettor--do not jam the shaft to make it fit.
- Use filtered tips when you are starting out.
- When transferring a small amount of solution
(e.g.: using a p20 to transfer 5 μL to a sample vial) to make a solution, it is
hard to see if all 5 μL is properly transferred (any volume less than
would be hard to see). It is
better to have certain amount of the solvent (e.g.: water) in the vial
first, and immerse the tip and deliver the 5 μL into the solvent, instead of into an empty
vial. You may also suck up
some amount of the solution after delivery and eject again to ensure no
residue is left behind on the side wall of the tip.