Cuvettes transmission properties

Optical Applications. Vitreous siUca is ideal for many optical appHcations because of its excellent ultraviolet transmission, resistance to radiation darkening, optical polishing properties, and physical and chemical stabiUty. It is used for prisms, lenses, cells, wiadows, and other optical components where ultraviolet transmission is critical. Cuvettes used ia scatter and spectrophotometer cells are manufactured from fused siUca and fused quart2 because of the transmissive properties and high purity (222). 

The processed monochromatic light is then directed into a sample chamber, which can accommodate a wide variety of sample holders. Most UV-VIS measurements on biomolecules are taken on solutions of the molecules. The sample is placed in a tube or cuvette made of glass, quartz, or other transparent material. Figure 5.7 shows the design of the most common sample holders and the transmission properties of several transparent materials used in cuvette construction. 

B A standard 3-mL cuvette. Courtesy of Beckman Instruments, Inc. C The transmission properties of several materials used in cuvettes. A = silica (quartz) B = NIR silica C = polymethacrylate D = polystyrene E = glass. 

UVA lS-spectroscopy is commonly used in the quality control laboratories of the flavour industry particularly for those products where colour characteristics are important. The possible measurement of the absorption or transmission of the samples in wavelength maxima as well as the intake of a spectrum over the entire wavelength area between 250-800 nm is important for the routine check of colour identity. By constant measuring parameters (cuvette, dilution, etc.) exact evidence of the colour intensity can be established. This analysis is very important for coloured flavouring preparations, fruit- and plant extracts or essential oils with colouring properties, as well as for testing for the presence of non permitted colouring materials [1],... 

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