DEVELOPMENT OF A PROCEDURE FOR QUANTITATIVE DETERMINATION OF VITAMIN C IN RAW MATERIALS USING THE UV–VIS SPECTROPHOTOMETRIC METHOD

Abstract

This study aims to develop and validate a direct UV–Vis spectrophotometric method for the quantitative determination of vitamin C in raw materials, using a phosphate buffer system at pH 5.4 combined with sodium oxalate as a stabilizing agent. The analytical procedure was evaluated in terms of specificity, linearity, accuracy, and precision. The results showed that the standard solution, test solution, and spiked solution exhibited a clear absorption peak at λmax = 265.5 nm. In contrast, the blank showed no significant absorption at this wavelength, demonstrating reasonable specificity. In the concentration range of 8–12 ppm, the calibration curve exhibited excellent linearity with a correlation coefficient R² = 0.99994. The recovery values ranged from 98% to 102% with RSD < 2%, indicating acceptable accuracy and repeatability. The validated method was then applied to quantify nine raw vitamin C samples (M1–M9), whose assay results were within the acceptable limit of 95–110% of the label claim. These findings confirm that the proposed UV–Vis method is reliable, cost-effective, and suitable for routine quality control of vitamin C in raw materials.