EFFECT OF INTERFERENCE ON AMPEROMETRIC GLUCOSE BIOSENSORS WITH CELLULOSE-ACETATE MEMBRANES

A new enzyme electrode concept featuring glucose oxidase (GOD) immobil ized on fine carbon powder in a fluid state and a cross-linked GOD enz yme layer has been developed. This enzyme electrode has been tested in vitro at 37 degrees C and has a lifetime of 3 months after which it c an be recharged with fresh enzyme. In vitro interference rests carried out on this sensor used with cellulose acetate membranes are describe d. Sulfur-free EDTA-treated cellulose acetate membranes (molecular wei ght cutoff at 1000) were used, some of which were coated with positive ly and negatively charged hydrogel layers. The sensors showed a stable and linear response to glucose concentrations >300 mg/ dL, in the pre sence glucose alone in the phosphate buffer medium and in the presence of interferences. The effects of ascorbic acid, bilirubin, creatinine , L-cystine, glycine, uric acid, and urea on the amperometric signal o f the sensor were studied. The cellulose acetate membrane coated with the negatively charged hydrogel layer provided good protection for til e enzyme electrode, especially in the presence of uric acid, bilirubin , and L-cystine.