Impact of weather on pipetting

Automated liquid handling performance can be optimized by adjusting system operating parameters, but the effect of environmental conditions on liquid handling quality is often under-appreciated. This study uses a two factor design (temperature and humidity) to investigate volumetric performance (precision and trueness) at environmental conditions from 15 ?C to 30 ?C and 30% to 80% relative humidity. Nine environmental conditions were tested, the mid point, four corner cases and four edge cases. Replicate testing was performed at the mid point and corner cases. The Tecan QC Kit, which is based on Artel?s ratiometric photometry, was used to make measurements at each set of environmental conditions. The precision (%CV), and trueness (%SE) is reported for each environmental condition using default liquid classes. The precision of the Tecan Freedom EVO was found to be insensitive to environmental conditions and performed within manufacturer?s limits over the entire range tested in this study (15 ?C to 30 ?C and 30% to 80% relative humidity). Over the range of this test, the trueness (systematic error) does depend on environmental conditions. Increased temperature and decreased relative humidity resulted in lower delivered volume. For the greatest accuracy in laboratory work, and particularly when operated outside of recommended temperatures, the automated liquid handling system should be tested and optimized for the local environment. The environmental effect on trueness exhibited a linear correlation with the ?evaporation potential? (the driving force for evaporation of the sample). The evaporation potential is dependent on both temperature and relative humidity. Use of this concept permits the experiment to be reduced from two factors (temperature and relative humidity) to one factor (evaporation potential).