A comparison of vitamin C content determination by chromatographic and spectrophotometric methods according to standard PN-A-040
Current Issues in Pharmacy and Medical Sciences Vol. 26, No. 4, Pages 443-447
ARTUR MAZUREK*, MARZENA WŁODARCZYK-STASIAK
Department of Analysis and Evaluation of Food Quality, University of Life Sciences, Lublin, Poland
Vitamin C performs many important functions in the human organism. Besides, it is used in the therapy and prevention of many diseases, which is why the methods applied to determine it should ensure the correct results. The present paper compares the results of vitamin C determination by means of the spectrophotometric method in agreement with the binding standard PN-A-04019:1998 and the proposed method of the reversed-phase high-performance liquid chromatography with spectrophotometric detection. The comparison was made using the method of calculating the proportion of mean results and the uncertainty of its determination. The analysis of a sample of the certified reference material BCR-43 was conducted. It was shown that because the content of dehydroascorbic acid was not considered, the result obtained by the standardized spectrophotometric method differs in a s ta tis ti cally significant way from the certified value, as opposed to the result obtained by the chromatographic method. Results of determining vitamin C content in blackcurrant, apple and grapefruit juices by means of the two methods indicate statistically significant differences. Compatible results were obtained only for orange juice. This is caused by insufficient selectivity of the spectrophotometric method of vitamin C determination. The suggested chromatographic method is more selective than the spectrophotometric method and it enables to consider the content of dehydroascorbic acid. That is why it should be recommended for routine determinations of vitamin C content.
vitamin C, ascorbic acid, dehydroascorbic acid, methods of determination