Many common laboratory procedures require quantitative pipettes and mechanical action air-displacement micropipettes are frequently used for this purpose. The design of these pipettes, however, makes their performance susceptible to sample temperature, as well as to environmental relative humidity and barometric pressure. The susceptibility to environmental effects is reflected in pipette calibration standards (e.g., ISO 8655-6 and ASTM E1154), which stipulate control and reporting of these environmental factors during pipette calibration.
Real-world usage of pipettes, however, often differs from calibration ideals. The work presented herein investigates the accuracy of micropipettes from three different manufacturers, ranging from 2 µL to 1000 µL. The first study investigated the accuracy of dispensed sample volumes when pipetting aqueous samples of different temperatures than the pipettes and tips. The second study investigated the effects of low humidity on pipetting accuracy, and the third study examined the impact of barometric pressure at high altitude.