DETERMINATION OF URINARY GLUCOSE BY A FLOW-INJECTION ANALYSIS AMPEROMETRIC BIOSENSOR AND ION-EXCHANGE CHROMATOGRAPHY

A practical biosensor system has been developed for the determination of urinary glucose using a flow-injection analysis (FIA) amperometric detector and ion-exchange chromatography. Glucose oxidase was immobili zed onto porous aminopropyl glass beads via glutaraldehyde activation to form an immobilized enzyme column. On the basis of its negative cha rge at pH 5.5, endogenous urate in urine samples was effectively retai ned by an upstream anion-exchange resin column. The biosensor system p ossessed a sensitivity of 160 +/- 2.4 RU muM-1 (RU or relative unit is defined as 2.86 muV at the detection output) for glucose with a minim um detection level of 10 muM. When applied for the determination of ur inary glucose, the result obtained compared very well with that of the widely accepted hexokinase assay. The immobilized glucose oxidase cou ld be reused for more than 1000 repeated analyses without losing its o riginal activity. The reuse of the acetate anion-exchange column befor e replacement would be about 25-30 analyses. Acetaminophen and ascorbi c acid were also effectively adsorbed by the acetate anion exchanger. The introduction of this type of anion exchanger thus greatly improved the selectivity of the FIA biosensor system and fostered its applicab ility for the determination of glucose in urine samples.