Kinetic determination of alkaline phosphatase activity based on hydrolytic cleavage of the P-F bond in monofluorophosphate and fluoride ion-selective electrode.

Alkaline phosphatase catalyzes the hydrolytic cleavage of the P-F bond in monofluorophosphate with the subsequent release of fluoride ions. A kinetic potentiometric method is described in which a fluoride ion-selective electrode is used for the sensitive and selective measurement of the released F- for the determination of alkaline phosphatase activity. It is shown that monofluorophosphate can be used as an alternative substrate for alkaline phosphatase. The reaction demonstrates a well-defined correlation with the hydrolysis of the P-O bond in 4-nitrophenyl phosphate. The serum alkaline phosphatase was determined in human serum samples by the potentiometric technique, and the results obtained compared well with a standard spectrophotometric method.