POTENTIOMETRIC DETERMINATION OF ALKALINE-PHOSPHATASE IN BLOOD-SERUM USING A HORDENINE-SENSITIVE MEMBRANE-ELECTRODE

A hordenine-sensitive membrane electrode was constructed and applied f or the determination of alkaline phosphatase (ALP) in blood serum. The method is based on the detection of hordenine formed by the enzymatic reaction of 4-O-phosphonohordenine (hordenine phosphate) with ALP. Th e hordenine electrode was constructed by incorporating sodium 3,5-bis( 2-methoxyhexafluoro-2-propyl)phenyl]borate as an ion-exchanger and 2-f luoro-2-nitrodiphenyl ether as a solvent mediator in a poly(vinyl chlo ride) membrane matrix. This is the first attempt to apply an ion-selec tive electrode for the assay of serum ALP. The results were compared w ith those obtained by colorimetry using phenyl phosphate as a substrat e.