Spectrophotometric assays are laboratory techniques used to measure the concentration of substances in a solution by analyzing the light they absorb. This method involves passing light through a sample and measuring the intensity of light that emerges. The amount of light absorbed is directly related to the concentration of the substance, allowing for quantitative analysis. These assays are commonly used in various fields, including biochemistry, environmental science, and clinical diagnostics. They can help determine the presence of specific compounds, such as proteins or nucleic acids, by using specific wavelengths of light that correspond to the absorption characteristics of those compounds.