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BIOLOGICAL ELECTRODES SPECIFIC FOR PHOSPHATE AND NITRITE IONS
Citation:
Guilbault, G. BIOLOGICAL ELECTRODES SPECIFIC FOR PHOSPHATE AND NITRITE IONS. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/4-76/034 (NTIS PB262233), 1976.
Description:
Biological electrodes have been developed for the selective analysis of phosphate and nitrate ions at micro-levels. A phosphate electrode was constructed by using two enzymes, alkaline phosphatase and glucose oxidase which were immobilized and mounted on the surface of the Platinum electrode. The competitive inhibition of phosphate ion on alkaline phosphatase slows down the hydrolysis of glucose-6-phosphate to glucose which is subsequently used by glucose oxidase as a substrate in the presence of molecular oxygen. The phosphate ion concentration in the reaction mixture was found to be proportional to the oxygen consumption. The assay of nitrite was accomplished with the use of nitrite reductase which catalyzes the reduction of nitrite into ammonia. Nitrite in the range of .0001 M-.01 M could be accurately determined with either soluble or immobilized enzyme using an air-gap electrode as sensor. Preparations of benzidine phosphate and hexammino cobalt nitrate in silicone rubber for liquid ion exchange and triphenyltin electrode have been attempted and results obtained were unsatisfactory due to their poor selectivity. This report was submitted in fulfillment of R 800359-02 by University of New Orleans under the sponsorship of the Environmental Protection Agency. Work was completed as date of 12-31-75.