cuvettes

Cuvettes are small, transparent or translucent containers used to hold liquid samples in analytical instruments, most commonly spectrophotometers and fluorimeters. They are designed to allow light to pass through the sample with a well-defined optical path, so that absorbance or transmission can be measured.

Materials vary with wavelength range and chemical compatibility. Borosilicate glass cuvettes are common for visible-light measurements; quartz cuvettes are required for ultraviolet measurements down to about 190 nm; disposable plastic cuvettes (polystyrene, polymethyl methacrylate, or polycarbonate) are used for routine analyses in the visible range.

Most cuvettes have a square or rectangular cross-section with two optically flat, parallel faces forming the light path. The standard path length is 1 centimeter, though other lengths such as 0.5 cm or 2 cm are available. The accuracy of the path length is critical for applying the Beer-Lambert law.

Handling and maintenance: cuvettes should be clean and free of scratches, fingerprints, or residues on the optical faces. They are typically cleaned with distilled water and mild detergents, followed by methanol or ethanol if needed; drying with lint-free tissue is recommended. Avoid touching the optical surfaces.

Variants: dedicated low-fluorescence cuvettes exist for fluorescence measurements; high-quality quartz cuvettes minimize UV absorption and autofluorescence; disposable plastic cuvettes are used for convenience and to minimize cross-contamination.