Spectrophotometric determination of vitamin C using Fe(II)-1-(2-pyridylazo)-2-naphthol complex

An extractive spectrophotometric procedure based on the complexation of reduced iron(II) with 1-(2-pyridylazo)-2-naphthol (PAN) for the estimation of micro amounts of vitamin C is described. The resulting complex is extracted into dichloromethane forming a reddish brown extract which shows an absorption band at 765 nm. Linear relationship between absorbance and concentration of ascorbic acid is observed up to 8.0 mu g ml(-1). Interference studies of different substances including sugars, vitamins and amino acids, metal ions and organic acids have been carried out. The utility of the method has been tested by analyzing some of the marketed products of vitamin C and biological samples.