Fe3O4-modified thick film carbon-based amperometric oxidase-biosensor
An amperometric biosensor was developed from screen printed carbon electrodes modified with magnetite (Fe 3 O 4 /SPCE) as the transducer element and Nafion-entrapped glucose-oxidase as the bio-recognition layer, cast by drop-evaporation. In a flowing stream (0.2 ml min -1 ) of phosphate buffer (pH 7.5/0.05 M), at a working potential of-125 mVvs. Ag/AgCl with an, injection volume of 100 μl, the biosensor has linear range of 7 - 150 mg l -1 glucose (r2 = 0.999), a sensitivity of 3.8 nA mg -1 l cm 2 , and a precision of 2% at 10 mg l -1 . Uric acid, xanthine and hypoxanthine at 10 and 100 mg l -1 do not cause significant error (± 1- 6 %) relative to 100 mg l -1 glucose. Ascorbic acid at 100 mg l -1 causes 10-14 % deviations. Dilute blood samples showed average recovery rate of 95 %. Thus, this model biosensor is precise, fairly sensitive and accurate.