Pipette tips and pipettes – an infallible system?

Many times experimental data were not reproducible even though all variables within the experimental procedure stood up to scrutiny. But was this really the case? 

In many cases the assumption is made that the pipetting system, consisting of pipette and pipette tip, is not a source of error as long as the tip fits the pipette. However, even if this is the case, it does not speak to the precision and accuracy of the pipetting result. This is because the international standard ISO 8655:2002 recommends the use of pipettes and tips by the same manufacturer. With good reason.

Only under these conditions can the client be certain that each lot of manufactured pipette tips represents exactly the calibration result described in ISO 8655:2002. This is not the case for a non-system vendor; a non-system vendor does not possess any system specifications to which he must refer. Hence, the user is forced to perform calibrations and, if necessary, adjustments of his pipette with the foreign tips – every time tips of a new lot number are used. 

The results of a large scale study in which a broad array of factors was identified which may negatively influence pipetting results can be found in Application Note 354 'The Tip of the Iceberg – how tips influence results' available here.