BIENZYMATIC POTENTIOMETRIC ELECTRODES FOR CREATINE AND L-ARGININE DETERMINATION

Ammonium-selective electrodes enzymatically sensitized for creatine an d L-arginine are presented. Enzyme layers of these biosensors contain two enzymes: urease and, as a second enzyme, creatinase or arginase de pendent on the analyte (substrate): creatine or arginine. The bienzyma tic layer with such a composition sequentially converts the analyte in to ammonium ions, which are detectable by the internal sensor. Monomol ecular and bimolecular bienzymatic layers immobilized directly on the ammonium sensitive membrane were used. The covalent binding of enzymes to the matrix of the ion-selective membrane made of the carboxylated poly(vinyl chloride) was performed using carbodiimide and glutaraldehy de. The extremely thin enzyme layers are strongly bound and easily pen etrable. Therefore the presented biosensors are stable and respond rap idly, t(95%), varies from 1.5 to 4 min. The linear ranges of both bios ensors were 0.1-30 mM and the detection limits were below 10(-5) M.