Spectrophotometric Quantitation of Vitamin C Using 3-hydroxy-2-(3-methyl-thiophen-2-yl)-4H-chromen-4-one as a Reagent

The proposed method for ascorbic acid (Vitamin C) determination is based on the absorbance of a Fe(III)- 3-hydroxy-2-(3-methyl thiophen-2-yl)-Chromen-4-One (HMTC) as complex in acidic medium, where the absorbance of the formed Fe(III)-HMTC chelate measured at 417 nm after extraction with chloroform gets decreased with the addition of ascorbic acid. This chelates formed immediately and the apparent molar absorptivity and Sandell’s sensitivity for vitamin C is found to be 4.413 × 104 dm3 mol-1 cm-1 and 3.984 × 10-7 g cm-2. Beer’s law is obeyed up to 1.2 μg ml-1 of ascorbic acid. The method has been successfully applied to determination of ascorbic acid in the pure state, dosage forms and multivitamin formulations.