Büretten

Büretten, known in English as burettes, are precision liquid delivery instruments used primarily in analytical chemistry to dispense known volumes of a titrant with high accuracy. They consist of a long, slender glass tube with a calibrated graduation marks along the length and a controllable stopcock at the bottom that regulates the flow of liquid.

Most Büretten are made of borosilicate glass and are designed to be mounted on a stand with a clamp. The stopcock can be glass or plastic (such as PTFE) and may be fitted with a removable valve to minimize leaks. They are commonly available in standard capacities of 50 milliliters, though smaller or larger versions exist. The inner surface is designed to be smooth to reduce adsorption and ensure clean, repeatable deliveries.

In operation, the burette is filled with the titrant and the initial volume is read from the scale at eye level, using the bottom of the meniscus as the reference point. The operator delivers the liquid in controlled, small increments, especially near the endpoint of a titration, and records the final volume. The delivered volume is the difference between the initial and final readings. Readability is typically 0.01 milliliters, though higher-precision microburettes offer finer scales.

Maintenance and calibration are essential for accuracy. Burettes should be rinsed with the titrant or compatible solvents, checked for air bubbles, and stored upright. Regular calibration against a reference standard ensures reliable measurements. Safety practices include handling glassware carefully to prevent breakage and using appropriate personal protective equipment.