Alpha-amylase hydrolyzes 1,4-glucosidic linkages in starch and other polysaccharides to form short chain oligosaccharides. The substrate used in reagent is 2-chloro-4-nitrophenyl-a-galactosylmaltoside (GALG2-CNP). The rate at which pnitrophenol is formed is directly proportional to the amylase activity in the sample. The resulting increase in absorbance can be measured spectrophotometrically at 405 nm.