Cuvettes

A cuvette (French: cuvette = "little vessel") is a small tube with a circular or square cross section, sealed at one end, made of plastic, glass, or fused quartz (for UV light) and designed to hold samples for spectroscopic experiments. A beam of light can pass through two clear sides and the absorbance value can be observed by using a spectrophotometer.

Performing ultraviolet–visible spectroscopy or fluorescence spectroscopy typically uses samples that are liquid - either a liquid substance or a substance dissolved in some solvent. The liquid sample is placed in a cuvette that is then placed in a spectrophotometer for testing. The cuvette can be made of any material that is transparent in the range of wavelengths being tested. Quartz is the highest quality, but various types of plastic or glass can also be used for economical reasons.

The size of the cuvette determines how long the light path is able to travel through the sample. For many applications, a 1 cm cuvette is used. Cuvettes typically have two parallel sides that are transparent so that the spectrophotometer light can pass through, but some tests can be performed by reflection and therefore only need a single transparent side. For fluorescence, two more parallel sides, perpendicular to the ones used for the spectrophotometer light, are needed for the excitation light. Cuvettes are typically 10 mm thick, allowing light to easily pass through. The thickness and sizes of cuvette affects the calculation of absorbance value. Some cuvettes have a glass or plastic cap for use with hazardous solutions, but others do not.

In 1934, James Franklin Hyde created a combined silica cell, which is free from other extraneous elements, as a liquefying technique of other glass products. In the 1950s, Starna Ltd. idealized the method to completely melt an optical segment of glass by using heat without deformation of its shape. This innovation has altered the production of inert cuvettes without any thermosetting resin. Before the rectangular cuvette was created, researchers used standard test tubes for laboratory work. As innovation motivated changes in technique, cuvettes were constructed to have focal points over ordinary test tubes.

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