A chemical assay refers to the analysis of a sample material, called analyte, using a set of chemical procedures. The objective is to determine the identity of the analyte's unknown components, isolate them and quantify them.
A chemical assay, as studied under the branch of chemistry called analytical chemistry, is divided into qualitative (identity) analysis and quantitative (amount of substance) analysis. Some of the methods used in qualitative analysis include extraction, distillation, precipitation and other methods that determine physical and chemical properties. Quantitative analysis involves the measurement of the isolated volume or weight of the substance. A chemical assay also utilizes instruments and techniques, such as spectroscopy, chromatography and electrophoresis, to measure the physical quantities of the analyte.