Volumetric pipette

Several sizes of volumetric pipette

A volumetric pipette or bulb pipette allows extremely accurate(of four significant figures) measurement of a volume of solution. These pipettes have a large bulb with a long narrow portion above with a single graduation mark as it is calibrated for a single volume (like a volumetric flask). Typical volumes are 1, 2, 5, 10, 20, 25, 50 and 100 mL. Volumetric pipettes are commonly used in analytical chemistry to make laboratory solutions from a base stock as well as to prepare solutions for titration.

ASTM standard E969 defines the standard tolerance for volumetric transfer pipettes. The tolerance depends on the size: a 0.5-mL pipette has a tolerance of ±0.006 mL, while a 50-mL pipette has a tolerance of ±0.05 mL. (These are for Class A pipettes; Class B pipettes are given a tolerance of twice that for the corresponding Class A.)

A specialized example of a volumetric pipette is the microfluid pipette (capable of dispensing as little as 10µL) designed with a circulating liquid tip that generates a self-confining volume in front of its outlet channels.

External links

• Helpful Hints on the Use of a Volumetric Pipet by Oliver Seely