AMPEROMETRIC ALANINE ELECTRODE

An amperometric enzyme electrode for L-Alanine determination was devel oped. The probe is based on a platinum electrode which senses the hydr ogen peroxide produced by the enzymatic reactions catalyzed by two enz ymes: alanine aminotransferase (ALT) and glutamate oxidase. Both the e nzymes were immobilized on polymeric membrane supports. Interferences were discriminated by additional protective membranes, Buffer, pH, cos ubstrate, temperature and immobilization procedures were optimized. Th e probe response was linear in the concentration range 10(-5) - 10(-3) mol/L with a detection limit of 2.10(-6) mol/L. Studies of enzymatic interferences were carried out. Glutamine interferred about 50% at a c oncentration of 5.10(-4) mol/L. Further studies were carried out to el iminate this interference. Analysis of alanine was performed in blood samples. Results compared with a HPLC procedure correlated well.