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A cuvette is a small tube of 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. The best cuvettes are as clear as possible, without impurities that might affect a spectroscopic reading. Like a test tube, a cuvette may be open to the atmosphere on top or have a cap to seal it shut. Parafilm can also be used to seal it.
Inexpensive cuvettes are round and look similar to test tubes. Disposable plastic cuvettes are often used in fast spectroscopic assays, where speed is more important than high accuracy.
Some cuvettes will be clear only on opposite sides, so that they pass a single beam of light through that pair of sides; often the unclear sides have ridges or are rough to allow easy handling. Cuvettes to be used in fluorescence spectroscopy must be clear on all four sides because fluorescence is measured at a right-angle to the beam path to limit contributions from beam itself. Some cuvettes, known as tandem cuvettes, have a glass barrier that extends 2/3 up inside, so that measurements can be taken with two solutions separated, and again when they are mixed. Typically, cuvettes are 10 mm (0.39 in) across, to allow for easy calculations of coefficients of absorption.
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Types of cuvettes
There are three different types of cuvettes commonly used, with different usable wavelengths:
- Glass, with a wavelength from 380 to 780 nm (visible spectrum).
- Plastic, with a wavelength from 380 to 780 nm (visible spectrum).
- Fused quartz, with a wavelength below 380 nm (ultraviolet spectrum).
- UV quartz has a usable wavelength of around 185 nm, and a matching tolerance of 1% at 220 nm.
- ES quartz has a usable wavelength range of 190 to 2,000 nm, and a matching tolerance of 1% at 200 nm.
- IR quartz has a usable wavelength range of 220 to 3,500 nm, and a matching tolerance of 1% at 2,730 nm.
- "An Introduction to Fluorescence Spectroscopy", http://www.bioch.ox.ac.uk/aspsite/services/equipmentbooking/biophysics/introfluor.pdf, Perkin Elmer Inc. 2006
- "Circular Dichroism (CD) Spectroscopy", http://www.bioch.ox.ac.uk/aspsite/services/equipmentbooking/biophysics/introfluor.pdf, Applied Photophysics Ltd., 2011
- Weisstein, Eric, W. "Birefringence" http://scienceworld.wolfram.com/physics/Birefringence.html, scienceworld.wolfram.com, Wolfram Research, 1996-2007
- "Quartz Glass: UV Quality Fused Silica", http://www.pgo-online.com/intl/katalog/quartz_glass.html, prazisions glas&optik