Spectrophotometry is a technique used to assess the amount of light a chemical substance absorbs by measuring the power of a light beam after it goes through a sample solution. The technique is based on the notion that each substance absorbs or emits light over a particular wavelength range. Measuring the intensity of a light beam can also be used to evaluate the quantity of a compound in a sample.
There are two main classes of spectrophotometers: single and double beam. A single beam spectrophotometer determines the absolute intensity of the light beam. A double beam spectrophotometer gauges the ratio of the light intensity on two different light paths.
Spectrophotometry is one of the best techniques of quantitative investigation in many fields, including chemistry, physics, chemical engineering and food science.