Which technique uses the absorption of light to determine the concentration of a substance?

Spectrophotometry is a technique that utilizes the absorption of light to determine the concentration of a substance in a solution. When a beam of light passes through a sample, certain wavelengths of light are absorbed by the substance, and the degree of absorption correlates directly with the concentration of that substance in the sample. The Beer-Lambert law quantifies this relationship, asserting that absorbance is directly proportional to concentration, allowing for quantitative analysis.

This technique is widely used in various fields including biochemistry, molecular biology, and environmental science, making it essential for determining concentrations of proteins, nucleic acids, and other biomolecules. By measuring the amount of light absorbed at specific wavelengths, researchers can determine how much of the substance is present in the solution.

In contrast, chromatography separates mixtures based on different affinities to stationary and mobile phases, electrophoresis separates charged molecules based on size and charge, and centrifugation separates components of a mixture based on density, none of which measure light absorption to determine concentration.