Application of voltammetry to determine vitamin C in apple juices

The cyclic voltammetric method, which is based on the redox properties of ascorbic acid, was adopted to determine the concentration of vitamin C in apple juices. Recorded on voltammograms, the oxidation current of ascorbic acid was linearly depend- ent on the ascorbic acid concentration (a linear calibration curve was found in the range of up to 150 mg ascorbic acid/100 cm 3 solution). The standard addition technique was used to determine the ascorbic acid concentration. To verify results, the titrimetric method was used. Differences between concentrations of vitamin C determined using the cyclic volt- ammetric and titrimetric methods are lower than 1 mg (in comparison to concentrations of ascorbic acid about 50 mg/100 cm 3 of juice). The method - easy for automation - can be used directly without special preparation of studied apple juices samples before measure- ment of the vitamin C concentration.