Spectrophotometric Determination of Antimony in Industrial Waste Waters with Iodide and Amidines

A new method has been developed for determination of trace amounts of antimony in industrial waste waters. It is based on the reaction of antimony(III) with iodide over 1.0–4.0M H2SO4, and extraction of the iodo complex with amidine(HA) into chloroform as a [Sb2I6HA] complex. The molar absorptivity of the complexes with 9 various amidines are found to be in the range of (4.1–6.8) × 103 1 mol−1 cm−1 at λmax. Of these, the simplest compound, N, N'-diphenylbenzamidine(DPBA) was chosen for detailed studies, and detection limit of the method with this compound is 0.2μg Sb/ml. The effect of diverse ions, solvents and acids was examined. Of various diverse ions tested, only Bi(III) causes serious interference in the determination of the metal. The method has been applied for the recovery of the metal to water samples containing up to 0.05 ppm Sb with relative standard deviation less than ±1.5%.