DETERMINATION OF SERUM ALKALINE-PHOSPHATASE ACTIVITY BY ELECTROCHEMICAL DETECTION WITH FLOW-INJECTION ANALYSIS

In this enzyme assay for kinetic measurement of alkaline phosphatase ( EC 3.1.3.1) activity in human serum by flow injection analysis with el ectrochemical detection (FIAEC), the substrate phenyl phosphate is enz ymatically hydrolyzed and the phenol produced is quantified by FIA-EC. The standard curve is linear over the range 40 to 500 U/1, and the pr edicted linearity is up to 1000 U/1. The CV is 5% over the range of th e assay. Correlation with the Sclavo Diagnostics nitrophenyl phosphate spectrophotometric technique gave an r of 0.98. This new technique re quires as little as 1 mul of serum. The FIA-EC method is not subject t o interference by hemolysis, icteria, or lipemia or by electroactive s ubstances such as urate, ascorbate, or acetaminophen. Sensitive measur ements free from spectrophotometric interferences are thus possible.