Errors Associated with Pipetting of Warm and Cold Liquids


Many  common  laboratory  procedures  require  the handling and  quantitative  dispensing of  reagents  at  various temperatures.  Mechanical  action  micropipettes  are  most often used for this routine task. The construction of these pipettes,  however,  makes  their performance susceptible to variations in temperatures of the samples dispensed.  This susceptibility to thermal  effects  is reflected  in pipette calibration standards (i.e. ISO 8655-6 and ASTM E1154), stipulating  stringent  control  of temperatures (20 ± 0.5  oC)  during   pipette   calibration,    and   also   requiring   that   all materials, including the liquids, be thermally equilibrated prior to the calibration.

However,  many  common  assay  protocols  require  the dispensing  of reagents  that are not in the specified temperature equilibrium. Two common examples are tissue culture applications,  which  employ  reagents  and buffers  at 37 oC, or assays with nucleic acid-based reagents at 4 oC or lower.

The work presented herein investigates the accuracy of micropipettes  from  three  different  manufacturers,  in  the most commonly  used range of 2 mL to 1000 mL, when used to pipet aqueous samples at various temperatures.

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