Application of the 1,2-Dihydroxybenzene-3,5-Disulfonic Acid for Separation and Preconcentration of Trace Iron and Determination by Eight Order Derivative Spectrophotometry

Iron is quantitatively retained on an adsorbent made by coprecipitation of 1,2-dihydroxybenzene-3,5-disulfonic acid (Tiron) and tetradecyldimethylbenzylammonium choride (TDBA) an microcrystalline naphthalene as a slurry or packed in a column, in the pH range 6.0-9.0 from a large volumes of aqueous solutions (up to 200 ml on microcrystalline naphthalene and up to 500 ml of aqueous solutions in the case of column method) of various samples. After filtration, the solid mass consisting of iron complex and naphthalene is dissolved in 5 ml of dimethylformamide and the metal determinate by eight derivative spectrophotometry. Alternatively iron can be quantitatively adsorbed on Tiron-TDBA-naphtalene adsorbent packed in a column at a flow rate of 0.5 to 5.0 ml/min and determined similarly. About 0.05 mg of iron can be concentrated in a column from 500 ml of aqueous sample, where its concentration is as low as 0.1 ng/ml. Various parameters such as the effect of pH, volume of aqueous phase and interference of a number of metal ions on the determination of iron have been studied in detail to optimize the conditions for its determination in standard alloys and biological samples.