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 electrochemical detection (FIAEC), the substrate phenyl phosphate is enzymatically 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 predicted linearity is up to 1000 U/1. The CV is 5% over the range of the assay. Correlation with the Sclavo Diagnostics nitrophenyl phosphate spectrophotometric technique gave an r of 0.98. This new technique requires as little as 1 mul of serum. The FIA-EC method is not subject to interference by hemolysis, icteria, or lipemia or by electroactive substances such as urate, ascorbate, or acetaminophen. Sensitive measurements free from spectrophotometric interferences are thus possible.