Transferability of Pipette Calibrations


One of the most obvious ways to maintain quality in a laboratory setting is the regular calibration of instruments. Regardless of the measuring instrument, a traceable calibration is achieved by comparison to a standard. If performed outside the laboratory, then the calibration must also be “transferable”. A transferable calibration is one that is still valid when the instrument is returned from the calibration lab into the users laboratory. Some calibrated items are very stable and the calibrations are easily transferred (e.g., weight sets and reference materials). Other calibrations (e.g., calibrations of balances) are less transferable, so must be performed in the users lab. In addition, calibrated instruments can be used improperly, so it is crucial that users be properly trained to use all calibrated instruments. Handheld pipettes are particularly susceptible to operator misuse and changes in environmental conditions (air temperature, barometric pressure, and relative humidity).  Because of these properties, pipette calibrations are poorly transferable and are best performed in the users environment.

Ideally, the pipette should also be calibrated using the same tips and same technique as the user employs in their ordinary work. Thus the resulting overall uncertainty of the volume measurement made using handheld pipettes may vary from location to location. Reducing  uncertainties depends on a variety of parameters. Ideally, a calibrated pipette in San Francisco, CA should perform with the same measurement uncertainty as one in Denver, CO, or anywhere else in the world. Calibration strategies for achieving this ideal are presented in this poster.

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