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R9 Laboratory SOP 890
CALIBRATION AND MAINTENANCE OF AUTOMATIC PIPETTES
Summary
The procedures described in this SOP apply to all automatic pipettes in the Region 9 laboratory including those used by the field team, biology team, chemistry team, and the FASP and must be followed by ESAT contractors as well as EPA employees. For the purpose of this procedure, automatic pipettes include all pipettes which operate by displacement and are used to make standards or reagents in the place of Type A volumetric glassware. For example, adjustable volume and fixed volume Eppendorf pipettes are included under this procedure while repipetters used to add acid to digestions are not included. Micro syringes are not included in this procedure as they are calibrated at the factory to NIST standards and are not subject to the same type of wear and failure that automatic pipettes frequently undergo.
The density of water at sea level (1.00g/mL) is used to verify the accuracy of automatic pipettes. Using an analytical balance accurate to 0.0001 g and verified against certified weights, a volume of water is weighed and the weight compared to the volume intended for delivery. For example, an adjustable pipette set on the 250 µL should deliver a volume of water with mass 0.250 g. For most purposes an error of 2 percent is acceptable.