Pipette Tips and Pipettes – An Infallible System?

In research involving pipetting, it has, on occasion, often been the case that experimental results were not easily reproducible, even though all variables within the experimental procedure have undergone a thorough review.  So in these instances, can it be said that all sources of error have truly been accounted for? 

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 guarantee that the pipetting result will be accurate. Therefore, with good reason, the international standard ISO 8655:2002 recommends using  pipettes and tips which are sourced from the same manufacturer.

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

The results of a large scale study, in which an array of factors were identified as having the potential to negatively influence pipetting results, can be found in Application Note 354 “The Tip of the Iceberg – how tips influence results” on the Further Information link below.