A reference method for measurement of alkaline phosphatase activity in human serum

Abstract

We present a reference method for the measurement of alkaline phosphatase, the culmination of optimization experiments conducted by a group of independent laboratories. The details of this method and evaluation of factors affecting the measurement are described. A metal ion buffer has been incorporated that maintains optimal and constant concentrations of zinc(II) and magnesium(II) ions. Final reaction conditions are: pH (30°C), 10.40 ± 0.05; 2-amino-2-methyl-1-propanol buffer, 0.35 mol/L; 4-nitrophenyl phosphate, 16,0 mmol/L; magnesium acetate, 2.0 mmol/L; zinc sulfate, 1.0 mmol/L; and N-(2-hydroxyethyl)ethylenediaminetriacetic acid, 2.0 mmol/L.