Editing Cuvette (section)

== Overview ==
[[File:2 sizes of cuvette.jpg|alt=A one milliliter and three milliliter cuvette.|thumb|1 mL and 3&nbsp;mL cuvettes]]
Traditional [[ultraviolet–visible spectroscopy]] or [[fluorescence spectroscopy]] uses samples that are liquid.  Often the sample is a [[Solution (chemistry)|solution]], with the substance of interest dissolved within. The sample is placed in a cuvette and the cuvette is placed in a spectrophotometer for testing. The cuvette can be made of any material that is transparent in the range of [[wavelength]]s used in the test.

The smallest cuvettes can hold 70&nbsp;microliters, while the largest can hold 2.5&nbsp;milliliters or more. The width determines the length of the light path through the sample, which affects the calculation of the absorbance value. Many cuvettes have a light path of {{convert|10|mm|in|sigfig=2|abbr=on}}, which simplifies calculation of the [[Attenuation coefficient|coefficient of absorption]]. Most cuvettes have two transparent sides opposite one another so the spectrophotometer light can pass through, although some tests use [[Reflection (physics)|reflection]] so only need a single transparent side. For fluorescence measurements, two more transparent sides, at right angles to those used for the spectrophotometer light, are needed for the excitation light.<ref>{{Cite journal |author=Perkin Elmer Inc. |date=2006 |title=An Introduction to Fluorescence Spectroscopy |journal=Spectroscopy |via=Retrieved 15 August 2013}}</ref> Some cuvettes have a glass or plastic cap for use with hazardous solutions, or to protect samples from air.<ref>{{Cite web |url=http://chemed.chem.purdue.edu/genchem/lab/equipment/spec20/cuvette.html |title=Cleaning and proper use of the cuvettes for the Spec 20 |date=2016-03-17 |website=chemed.chem.purdue.edu}}</ref>