Colorimetric determination of vitamin C using Fe(II)-5-Chloro-7-iodo-8-hydroxyquinoline complex

Abstract

An extractive spectrophotometric procedure based on the complexation of reduced Iron (II) with 5-Chloro-7-iodo-8-hydroxyquinoline (CIHQ) for the estimation of micro amounts of vitamin C is described. The resulting complex is extracted into chloroform to give a reddish brown extract which shows an absorption band at 485 nm. Linear relationship between absorbance and concentration of ascorbic acid is observed up to 0.8 μg ml -1 . Interference studies of different substances including sugars, vitamins and amino acids, metal ions and organic acids were carried out. The utility of the method was tested by analysing some of the marketed products of vitamin C.