DEVELOPMENT OF A CHEMILUMINESCENCE DETECTOR WITH PHOTODIODE DETECTIONFOR FLOW-INJECTION ANALYSIS AND ITS APPLICATION TO L-LACTATE ANALYSIS

A low cost chemiluminescence detector with a photodiode for flow-injec tion analysis (FIA) of L-lactate in food was developed for quality con trol in food industry. In this system, L-lactate is oxidized by the en zymatic reaction with L-lactate oxidase immobilized on the column to p roduce hydrogen peroxide. Then chemiluminescence caused by mixing hydr ogen peroxide with the chemiluminescence reagent was detected by the p hotodiode. This light intensity was proportional to L-lactate concentr ation. For detecting weak chemiluminescence efficiently a flow-through cell of the detector was specially designed. A photodiode was used fo r the purpose of reducing the costs of FIA systems instead of a photom ultiplier tube. As a result, a linear working curve was obtained from 10(-7) to 10(-3) mol l(-1) L-lactate concentration. We applied the pre sent system with a photodiode detector for food samples and compared t he results with those obtained by the conventional HPLC method. The da ta obtained by the present FIA method were fairly in good agreement wi th those obtained by the conventional HPLC method. The correlation fac tor and regression line between both methods were 0.992 and Y = 1.07X - 0.15, respectively. The present FIA system with the photodiode detec tor is available as a simple, easy-handling instrument for quality con trol in food industry.