How to accurately pipet blood? - (Aug/07/2010 )

Any tips on accurately pipetting whole blood? I need to pipette about 1.5 mL as accurately as possible. Thanks.

you can use a 1000 microliters micropipette, just do 2 steps with 750 microliters

you can also post your question in the hematology section of BioForum

If you really need accuracy (or at least repeatability) then you can weigh your samples and adjust to constant weight. This will more accurate than volume.

Hi, I posted this in the general forum, but it was suggested that I try reposting it here.

Any tips on accurately pipetting whole blood (actually washed red blood cells)? I need to pipette about 1.5 mL as accurately as possible. Thanks

Is there something particularly difficult in pipetting washed red cells as opposed to, say, pipetting 1.5 ml of saline? If you're trying to achieve equal numbers of cells per aliquot from different samples, accurate volume is not the answer without knowing the number of cells per volume unit.

HomeBrew on Thu Aug 19 00:47:19 2010 said:

I think I'm losing some volume because it's viscous. I need an accurate volume because I'm using the red blood cells to dilute a standard out (1.5mL red blood cells to 1.5mL of standard).

Repeat pipetting is not the way to go - errors compound. I would use a 2ml syringe or weigh it as Phage suggested.

you can use wide bore pipette tips or cut part of the tip off of the pipette tip to ensure that the effects of viscosity are reduced.

Gradstudent78 on Thu Aug 19 02:32:04 2010 said:

In that case, a positive displacement pipette is better than an air displacement pipette. A syringe might also be a better choice (as was suggested) if the accuracy of the graduations on a syringe is high enough (I don't know how accurate a typical syringe's markings are, nor how accurate the measurement-to-measurement reproducibility will be with a syringe).