Serum alkaline phosphatase assay with paired emitter detector diode

A simple multicommutated flow system based on optoelectronic detector, three valves and peristaltic pump only has been developed for photometric determination of alkaline phosphatase activity in human serum. A miniaturized, compact flow-through detector dedicated to selective photometric detection of product formed in the course of the enzyme assay has been constructed using two paired light emitting diodes. The proposed analytical procedure based on kinetic methodology of enzyme activity detection and stopped-flow methodology of two-point measurements eliminates interferences caused by intense color of real samples and impurities present in commercial reagents. After optimization the system allows reproducible, mechanized analysis of human serum in relatively short time (8–9 samples per hour). Volume of serum required for single determination is 0.05 mL only. The system validated with real clinical samples is useful for determination of enzyme activity in human serum at physiological and pathological levels.