EVALUATION OF A BIOSENSOR AND COLUMN LACTATE OXIDASE IMMOBILIZATION FOR PHYSIOLOGICAL ANALYSIS USING FLOW-INJECTION AMPEROMETRY

A flow-injection system with anodic amperometric detection for I-lacta te determination in natural body fluids was optimized by comparison of various methods of enzyme immobilization and the elimination of inter ferences. Acceptable results were obtained using a biosensor in a wall -jet-through detector with a platinum disk electrode covered with an N ation membrane and a polyester membrane containing immobilized lactate oxidase, or in a similar system having the enzyme immobilized in a sm all column on a glass support. For the system with on-line predilution , a linear response was observed, usually up to 15 mM 1-lactate at a s ampling rate of approx. 100 samples/h for 10 mu l sample volume. Ascor bate and urate interferences have been examined and were successfully rejected at values exceeding the physiological level. Results of 1-lac tate determination in natural samples were compared with those obtaine d using a DuPont Dimension Analyser.