Description
The method is applicable for determination of amounts of iron normally occurring in food products. Determination of iron in low concentrations, however, shows poor reproducibility. Cu2+ -ions interferes with iron when they occur in fivefold excess of iron. The formation of iron complex is not influenced by fivefold excess of Hg2+, Cd2+, Pb2+ and Mn2+ or by tenfold excess of Sn2+, Sn4+ and Zn4+ added separately. The organic matter is decomposed by ignition at 550ºC, followed by reduction of ferric ions by hydroxyl ammonium chloride to ferrous ions and is determined as iron-3-(2- pyridyl)-5,6-bi(4-phenyl sulphonic acid)-1,2,4-triazine complex. Spectrophotometric measurement of the red- coloured complex is made at a wavelength of 562nm. (NMKL 116)