Selecting a Cuvette on Amazon.com
A cuvette, also known as a cuvet, sample cell, or absorption cell, is a specialized test tube for holding samples undergoing optical analysis by instruments such as spectrophotometers and turbidity meters. Capacity is usually measured in milliliters or microliters. The shape of a cuvette may be cylindrical or, when minimal light refraction is important, it may be rectangular. In order for light waves to travel through the cuvette, it should be as clear as possible for optimum results. The path length of a cuvette is a measure of the distance that light travels through a sample. Certain rectangular cuvettes are clear only on a pair of opposite sides, providing a constant path length by allowing only a single beam of light to pass through. This is ideal for spectrophotometry, which measures the amount of light of a specified wavelength that passes through a sample. When used in a fluorometer, a cuvette must have all four sides clear because fluorescence is measured at a right angle to the path length.
Transparent quartz, glass, and plastic are materials from which a cuvette may be made, with each providing different optical properties. A quartz cuvette, for example, is used for absorbance measurements in the ultraviolet light range (wavelengths below 380nm) where glass and plastic become opaque. The transmission properties of a quartz cuvette are superior to other materials. Glass and plastic cuvettes are used for absorbance measurements in the visible light range (wavelengths from about 380 to 780nm), with glass generally providing greater precision. For testing in which speed is more important than accuracy, a disposable plastic cuvette may be selected. Compatibility of the sample being tested with the material of the cuvette is also a consideration. To perform properly, a cuvette must be free of cracks and impurities in the material which could skew results. Some cuvettes include a cap or stopper for sealing. Cuvettes are used in laboratory and field applications.