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P9010
Liquid Delivery Errors – The Impact of Laboratory Conditions on Pipetting Performance
Presenter Keith Albert, ARTEL, USA
Additional Authors: A. Bjoern Carle, Doreen A. Rumery, Aaron B. Davis, Geoff A. Sawyer, John Thomas Bradshaw
Mechanical action micropipettes are used for many routine laboratory tasks, including the quantitative measurement and dispensing of analytical samples and reagents. The design and construction of these devices renders their performance susceptible to the environmental parameters of temperature, barometric pressure and humidity which must be tightly controlled during calibration. In most laboratories, however, pipettes are used under conditions, which often deviate significantly from the specified calibration conditions. Experimental protocols often require pipetting analytes or samples, which are not in thermal equilibrium with the pipette and tips (e.g. refrigerated reagents, warm liquids in tissue culture, or hot PCR samples).
Furthermore, the relative humidity in most laboratories deviates from the official calibration value (50 %), depending on the geographic location, the type of laboratory and equipment used therein, as well as the type of heating or air-conditioning systems installed.
Employing high-precision ratiometric photometry, errors induced by these “environmental” parameters on the accuracy and precision of pipetted sample volumes were investigated. Statistically significant errors of up to 80% deviation from the target volumes were observed when samples of different temperatures (4 deg C, 37 deg C, and 60 deg C) were pipetted. Changes in relative humidity were found to cause errors in excess of 20 % in the delivered sample volumes.
This research investigates and highlights the magnitude of errors, which are likely to be incurred by following “standard” procedures in “regular” laboratory settings. While error analyses are most commonly focused on reagent or analyte quality and sample preparation, environmental parameters are often neglected as contributing error to pipetting and liquid handling steps.