Rainin Pipetman P-2 Manual

Contents

Rainin Pipetman P-2 Manual Manual pdf 8 page image

6Pre-Rinsing RecommendedSome solutions (e.g. serum, protein-containing solutions,and organic solvents) can leave a film on the inside tipwall, resulting in an error larger than the tolerance speci-fied. Since this film remains relatively constant in succes-sive pipettings with the same tip, excellent precision maybe obtained by refilling the tip and using the refilled vol-ume as the sample. Successive samples from this sametip will exhibit good reproducibility (low variance).Reverse Mode PipettingAnother way of reducing error due to film retention is re-verse mode pipetting; the operating sequence is reversed:1. Mount a disposable tip on the pipette shaft.2. Press the pushbutton fully to the second stop.3. Immerse the tip in liquid and return the plunger slowlyto the full up position. Wait a moment for the liquidcolumn to reach equilibrium in the tip.4. Wipe any excess liquid from the outside of the tipwithout touching the orifice.5. To dispense, rest the end of the tip against the vesselwall and press the plunger to the first stop. Hold thisposition a few seconds, or long enough for the liquidcolumn to reach equilibrium again.6. Remove the tip from the receiving vessel withoutblowing out the remaining liquid.7. Return excess sample in the tip to the original samplecontainer, if desired. Discard the used tip.Pipetting Liquids of Varying DensityPipetman lets you compensate for solutions of densitymuch different from water, by setting the volume slightlyhigher or lower than that required. The compensationamount must be determined empirically.E.g., if pipetting 10 μL of CsCl solution, you determinethat the volume delivered is actually 8.5 μL (≥5 samples).Try changing the volume setting to 11.8 μL and repeat themeasurements. If the volumes delivered are still not closeenough to 10 μL, make another slight volume adjustmentuntil the measurements are as desired.Very dense liquids may not be suitable for air displace-ment pipetting. Use Microman® positive displacementpipettes for these liquids.