Ultraviolet/Visible (UV/VIS) Spectrophotometer is an analytical instrument that measures the intensity of light passing through a sample solution and compares it to the intensity of light before it passes through the sample. This measurement is based on the principle that molecules absorb specific wavelengths of light in the ultraviolet (195-1020 nm)  regions of the electromagnetic spectrum.

The key components include a light source, a monochromator to select specific wavelengths, a sample holder (cuvette), and a detector. When a sample is placed in the light path, molecules absorb energy, promoting electrons to higher energy states. The amount of light absorbed is quantified as absorbance (A), which is directly proportional to the sample’s concentration (Beer-Lambert Law).

This technique is primarily used for quantitative analysis, such as determining the concentration of a known analyte in solutions, studying reaction kinetics, and assessing sample purity. It is renowned for its simplicity, accuracy, and rapid results, making it a fundamental tool in chemistry, biochemistry, environmental science, and pharmaceutical laboratories.