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What is a Burette?


For dispensing liquids in specific volumes, lab workers have the option of choosing a burette or a pipette. We’ve talked about pipettes before, so in this post, we’ll look at burettes and why they may be right for you. 

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What is a Burette? 

Used for quantitative analysis, a burette is a graduated glass tube with a valve (or stopcock) to control the flow. It dispenses small volumes of liquid, or sometimes gas, with high accuracy. When measuring liquids, the stopcock is at the bottom of the glass tube; for gases, the stopcock is at the top. For a gas burette, the tube is filled with a fluid (such as water, oil or mercury) and the bottom of the tube is attached to a reservoir of the same fluid. Gas is measured by the amount of displaced fluid. 






The capacity of burettes is measured in milliliters, typically ranging from 5 mL to 100 mL. Like pipettes, burettes (sometimes spelled burets) are available in two classes, A and B. Class B offers ±mL tolerances twice that of Class A. 

There are three different types of burettes: 

  • volumetric burettes  
  • piston (or digital burettes) 
  • electronic burettes 

Volumetric burettes are made from glass or plastic, with a volume scale on the burette wall for reading results. 

Piston burettes, which are also called digital burettes, utilize a syringe design. Like volumetric burettes, piston burettes are manually controlled. 

Electronic burettes are the most accurate, offering an electronic display and motor-controlled piston movements. 

What is a Burette Used For? 

Burettes are usually used to measure and dispense small volumes of liquid (referred to as aliquots), though there are burettes designed to measure small volumes of gas. They’re useful in chemical analysis for titration.  

Burettes vs. Pipettes 

So if you can use burettes or pipettes for dispensing liquids, what’s the difference? 

For one, their release mechanism: burettes utilize a stopcock at the bottom, while pipettes release the desired amount of liquid by lessening the vacuum like a dropper. More importantly, while pipettes can pick up and deliver fluids, burettes can only release them. 

Mobility also factors in. A burette is typically stationary, while pipettes are movable. 

Sonic Supply offers burettes from several manufacturers, including DLAB, Microlit and United Scientific Supplies Inc

 

Feel free to contact us with any questions about burettes or how to select the right one for your lab. 

To see our full list of burettes, click here.

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