Confused about all the options for pipettors? Let’s start with a definition of the pipette or pipet. Volumetric pipettes are used to deliver extremely accurate liquid volumes of from 0.50ml to 50.00ml. Tolerance for the 50.00ml volumetric pipette is +/- 0.1% for Class A. Tolerances for Class A and Class B volumetric pipettes are set by ASTM E969.
Serological pipettes are available from 1ml to 10ml and are graduated. The tolerances of these pipettes runs from 0.3% to 2%.
Pasteur pipettes are only meant for liquid transfer and have no graduations or volume markings.
Piston driven air displacement pipettes are used for accurately delivering volumes between 1ul and 5000ul. These pipettors are used largely in biochemistry and microbiology where sample volumes can be very small. There are fixed volume pipettes and adjustable volume pipettes. Adjustable pipettes have a range of volumes for which they are designed. In general accuracy of a microliter pipette ranges from 0.5 % to 5%. Accuracy increases with increasing volume and the coefficient of variation (% CV) decreases with increasing volume. Electronic Pipettors significantly reduce operator strain from repetitive pipetting. Multichannel pipettors are also available; multi pipettors can have up to 12 channels. Some of the manufacturers of air displacement pipettors are: Eppendorf, BrandTech, Labnet, Biohit, Wheaton, and Thermo Scientific to name a few. For instructions on how to pipette please refer to this link for Jamie Welch at EnviroLogix, Inc. I will discuss pipette tips at a future date.