A simple and highly sensitive direct spectrophotometric method was developed for the determination of L-ascorbic acid. Potassium cyanide (9.21x10-5 mol dm-3) was used to stabilize ascorbic acid in aqueous medium. The molar absorptivity of the proposed method, which does not require an extraction procedure, was 1.38x104 dm3 mol-1 cm-1 at 264 nm. Beer’s law was obeyed in the concentration range of 0.26 – 12.0 μg ascorbic acid cm-3. Th e relative standard deviation was 1.40 % for the determination of 8.0 μg ascorbic acid cm-3 (n = 7). The substances commonly found in vitamin C products do not interfere with the determination of ascorbic acid. Other vitamins and organic acids interfere. The proposed procedure was successfully applied to the determination of ascorbic acid in pure form and vitamin C preparations.

spectrophotometry; L-ascorbic acid; potassium cyanide; stabilizer

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