Enzymatic Assay by Flow Injection Analysis with Detection by Chemiluminescence: Determination of Glucose,Creatinine, Free Cholesterol and Lactic Acid Using an Integrated Fia Microconduit

Abstract

A miniaturized flow injection system for the determination of D-glucose, L-lactic acid, creatinine and free cholesterol is described. All substrates are degraded enzymatically by means of oxidases which, along with ancillary coenzymes (creatinine assay), are immobilized on controlled porosity glass and incorporated into small PVC column reactors. The hydrogen peroxide generated by the individual oxidases is determined by chemiluminescence with an alkaline reagent containing luminol and hexacyanofer rate (III). The injection valve, flow channels, enzyme reactor and light detector are integrated into a FIA microconduit. The detection limits were 0.03 mg glucose/dl, 0.03 mg lactate/dl, 0.3 mM creatinine and 0.5 mg cholesterol/dl. The enzyme reactors all showed little change in activity over a 3 months period of operation and were found fully compatible with serum samples.