BIOSENSOR BASED ON ASCORBATE OXIDASE FOR ASCORBIC ACID DETERMINATION

A new biosensor design, consisting in ascorbate oxidase (AOx) and bovine serum albumine immobilization on the membrane of an oxygen electrode, followed by cross-linking with glutaraldehyde (GA), was proposed for ascorbic acid (AA) determination. The biosensor was optimized regarding the enzyme loading and GA concentration. The best bioelectroanalytical parameters were obtained when 1.25 % GA and 157 U/cm(2) AOx were used: sensitivity of 328 +/- 67 mu A/M, linear domain up to 0.4 mM and detection limit of 50 mu M. The biosensor was used to estimate the AA concentration in synthetic samples and the results were in good agreement with those obtained by using the reference method based on 2,6 dichlorophenolindophenol (relative error similar to 1.1 %).