THE USE OF DIFFERENTIAL MEASUREMENTS WITH A GLUCOSE BIOSENSOR FOR INTERFERENCE COMPENSATION DURING GLUCOSE DETERMINATIONS BY FLOW-INJECTIONANALYSIS

A novel detection system for the determination of glucose in the prese nce of clinically important interferents, based on the use of dual sen sors and flow-injection analysis (FIA), is described. The normalisatio n methodology involves measurement of the interference signal at a ref erence sensor; this signal can then be subtracted from the glucose sen sor signal (post-run) to give a corrected measurement of the glucose c oncentration. The detection system consists of a thin layer cell with dual glassy carbon working electrodes. One electrode was surface modif ied to act as a glucose biosensor by immobilisation of glucose oxidase (GOx) (from Aspergillus niger) with 1% glutaraldehyde and bovine seru m albumin. The second electrode (glucose oxidase omitted) was utilised to measure the interference signal responding only to electroactive s pecies present in the injected sample. A computer controlled multichan nel potentiostat was used for potential application and current monito ring duties. The sensor responses were saved in ASCII format to facili tate post-run analysis in Microsoft Excel. Cyclic voltammetry (CV) was utilised to investigate the manner in which the interference signal c ontributed to the total signal obtained at the biosensor in the presen ce of glucose. The kinetic parameters I-max and the apparent Michaelis -Menten constant, K-m', were calculated for the sensor operating under flow-injection conditions.