A new, selective and accurate direct ultraviolet spectrophotometric method was developed for the determination of L-ascorbic acid in pharmaceuticals. The oxidation of L-ascorbic acid by iodate in an acidic medium was used as a means of correcting for background absorption. The molar absorptivity of the proposed method was found to be 8.71x103 dm3 mol-1 cm-1 at 250 nm. Beer’s law was obeyed in the concentration range of 0.46 – 16.00 μg cm-3 for L-ascorbic acid. The relative standard deviation was 0.67 % for a concentration of 8.00 μg cm-3 of ascorbic acid (n = 7). The ingredients commonly found in vitamin C and multivitamin products did not interfere. The proposed procedure was successfully applied to assays of L-ascorbic acid in pharmaceutical preparations. The results obtained with the proposed method showed good agreement with those given by the titrimetric method using iodine.

L-ascorbic acid; iodate; ultraviolet spectrophotometry

Published by University of Zagreb, Faculty of Agriculture, Zagreb, CROATIA
Sponsored by Ministry Science and Education of the Republic of Croatia