Spectrophotometry in the UV-VIS is one of the oldest methods of instrumental chemical analysis. There are two ranges of light: ultraviolet range - UV and visible light - the VIS. UV-VIS spectrophotometers are widely used in analytical chemistry, medicine, biology and research. Determination of the concentration of analyte is obtained by measuring the absorbance of the solution containing the analyte.
Spectrophotometers generally can be divided because of the construction: single beam spectrophotometers in which the light beam first passes through the reference sample, and then after replacing the cuvette, through sample to be tested and double beam spectrophotometer in which the beam is divided by the system into two identical beams passing parallel through reference sample and the test solution.