Accuracy and Precision in Pipetting Viscous Solutions

Scientists know that viscous solutions do not behave the same way as aqueous solutions during pipetting. Master mix, glycerol, and polyethylene glycol are examples of liquids that are more viscous and do not flow as easily as water-based fluids. Adjusting pipetting technique to compensate for differences in fluid properties is critical to ensuring the quality and reproducibility of lab tests and assays.

To assist scientists who work with these solutions, Artel has released a poster of best practices- “Pipetting Viscous Solutions” - that details how such liquids behave differently during pipetting and what adjustments to equipment and technique can be made to ensure accurate volume delivery. It complements the popular “Ten Tips ” poster, which provides guidance for the dispensing of aqueous solutions.

One technique that significantly affects accuracy, and the first tip included in the poster, is forward vs. reverse mode dispensing. Forward mode pipetting of viscous material frequently results in under-delivery due to the film of solution that remains inside the pipette tip. Reverse mode pipetting corrects for this, resulting in a much more accurate dispense.