Development of a chemiluminescence detector with photodiode detection for flow-injection analysis and its application to l-lactate analysis

A low cost chemiluminescence detector with a photodiode for flow-injection analysis (FIA) of l-lactate in food was developed for quality control in food industry. In this system, l-lactate is oxidized by the enzymatic reaction with l-lactate oxidase immobilized on the column to produce hydrogen peroxide. Then chemiluminescence caused by mixing hydrogen peroxide with the chemiluminescence reagent was detected by the photodiode. This light intensity was proportional to l-lactate concentration. For detecting weak chemiluminescence efficiently a flow-through cell of the detector was specially designed. A photodiode was used for the purpose of reducing the costs of FIA systems instead of a photomultiplier tube. As a result, a linear working curve was obtained from 10−7to 10−3 mol l−1 l-lactate concentration. We applied the present system with a photodiode detector for food samples and compared the results with those obtained by the conventional HPLC method. The data obtained by the present FIA method were fairly in good agreement with those obtained by the conventional HPLC method. The correlation factor and regression line between both methods were 0.992 and Y = 1.07X-0.15, respectively. The present FIA system with the photodiode detector is available as a simple, easy-handling instrument for quality control in food industry.