The Tip of the Iceberg: How Pipette Tips Influence Results - Perfect Geometry Makes a Difference

Ulrike Gast, Eppendorf AG

Laura Koch, Eppendorf Polymere

We performed a study including standard tips from different manufacturers in order to investigate the tip-related influences on the pipetting result. The study showed a dramatic impact of the tip on the pipetting accuracy. Small volume pipetting accuracy is significantly influenced by the quality of the tip
orifice. Any impairment of geometry and shape can lead to retention of liquid.

Tip-related influencing factors on pipetting results can be compared to an iceberg. Some influencing factors are easy to observe, like the necessity for high tip attachment forces in order to achieve a secure and tight fit of non-recommended tips on the pipette cone. Other factors stay rather unknown, like the geometry of the tip orifice. Part 1 of this series of Application Notes described pipette and tip as a system which may not perform within permissible error tolerances with all tips.

This is in concert with ISO 8655 which regards pipette and tip as a system and the use of other tips than recommended as a system disruption. In part 1, the air-cushion size was detected to be the main influencing factor on bigger volumes like 1,000 μL. In contrast, with 10 μL tips other factors come into play. Here, the quality of the tip's orifice was found to be of high importance. For further investigation, the orifices of tips from different manufacturers were scrutinized and compared to calibration results.

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