Technology of manually operated sampler pipets.

We have evaluated the performance of manually operated sampler pipets. Twenty-four instruments of various construction, manufacture, and delivery volume were evaluated. Pipet-delivered water and serum were repeatedly weighed under controlled environmental conditions, and precision and accuracy assessed. The pipets often failed to meet the manufacturer’s stated tolerance limits. Consumers should calibrate these instruments in their own laboratories. Some of the manufacturer’s recommendations for optimal performance are challenged. The manual samplers can substitute for oral pipets and permit safe, inexpensive, simple, and rapid transfer of liquids, if the user recognizes their operational characteristics and limitations in accuracy and precision.