Spectrophotometric Determination of Ascorbic Acid in Pharmaceuticals by Flow Injection Analysis Using Brown Mono 1, 10-Phenanthroline-Iron (III) Complex as An Oxidant

A single channel flow injection manifold for spectrophotometric determination of ascorbic acid is described. The method is based on the on-line reduction of mono (1,10 Phenanthroline)-iron (III) complex to tris (1,10-Phenanthroline) - iron (II) complex by reducing action of dienol group of ascorbic acid and the absorbance of the resultant tris chelate was monitored at 510 nm. The effects of reaction coil length, sample volume, flow rate and the reagent concentration on the analytical signal are discussed. A calibration curve for ascorbic acid over the range 0-50 ppm, under optimized conditions is reported. The proposed method was sensitive, rapid (sample rate of 200 s/h) and reproducible (R.S.D 0.5%, n=15). Satisfactory results were obtained in the determination of ascorbic acid in Pharmaceutical preparations.