Detection Instrument: Spectrophotometer
Test Principal: Production of o-nitrophenol and galactose by o-nitrophenol-?-D-galactoside (ONPG) catalyzed by sodium dependent ?-D-galactosidase. The amount of o-nitrophenol is directly proportional to the concentration of sodium ion in the sample. The o-nitrophenol is yellow in alkaline environment. The increase of absorbance is determined at 405 nm, and the content of sodium ion is calculated indirectly.
