FLOW-INJECTION ANALYSIS OF L-LACTIC ACID USING AN ENZYME-POLYION COMPLEX-COATED ELECTRODE AS THE DETECTOR

The concentration of L-lactic acid was determined by a combination of flow injection analysis with amperometric enzyme sensor detection. The enzyme sensor was prepared by immobilizing lactate oxidase in a layer of polyion complex consisting of poly-L-lysine and poly(4-styrenesulf onate). The sensor-based system can be used for the determination of L -lactate concentration up to 6 mM with a sampling rate of 120 h(-1), a nd is stable for 8 weeks after 1000 L-lactate injections. The permsele ctivity of the polyion complex matrix is effective for reducing the re sponse from electrochemical interferents such as L-ascorbic acid, uric acid and acetaminophen.