3. How do I check my pipette?

3.1 Acceptability criteria

The standard dealing with gravimetric verification is EN ISO-8655. This standard gives acceptability criteria based on nominal volumes, which is debatable as they are expressed as absolute values. For example, for a 1,000 µl pipette (nominal volume = 1,000 µl), the standard gives an acceptable accuracy error of 8 µl. It may seem reasonable to accept 8 µl of error at 1,000 µl (i.e. 0.8%), but most current 1,000 µl pipettes have a range of use from 100 µl to 1,000 µl, and the standard recommends checking three volumes, one of which should be...