Amperometric detection of ascorbic acid in honey using ascorbate oxidase immobilised on amberlite IRA-743

A differential amperometric method for the specific determination of ascorbic acid in honey was developed by association of a flow injection analysis (FIA) system and a tubular reactor containing the ascorbate oxidase enzyme immobilised. A gold electrode modified by electrochemical deposition of palladium was employed as working electrode. Ascorbic acid was quantified in seven samples of commercial honeys using a potential of +0.60 V vs. Ag/AgCl(sat). The linear dynamic range in ascorbic acid extends from 1 to 50 mu mol L-1, at pH 7.0. At flow rate of 1.5 mL min(-1) and injecting 250 mu L sample volumes, a sampling frequency of 180 determinations per hour is afforded. The detection and quantification limit of this method are 0.14 and 0.49 mu mol L-1, respectively. The samples analyses were compared with the volumetric method, and showed an excellent correlation between the methods. (C) 2012 Elsevier Ltd. All rights reserved.