Spectrophotometry is an analytical technique that allows determining the concentration of a compound in solution. It is based on the principle that molecules absorb electromagnetic radiation and in turn that the amount of light absorbed depends linearly on the concentration. A spectrophotometer is used to measure the amount of light absorbed by a solution.
That is, spectrophotometry refers to the measurement of relative amounts of light absorbed by a sample, as a function of wavelength. It is characterized by its accuracy, sensitivity and its applicability to molecules of different nature (pollutants, biomolecules, among others) and aggregation state (solid, liquid, gas).