Solid phase extraction and flame atomic absorption spectroscopic determination of trace amounts of iron(III) using octadecyl silica membrane disks modified with 2-mercaptopyridine-1-oxide

A simple and selective method for rapid extraction and determination of trace amounts of iron(III) using octadecyl-bonded silica membrane disks modified with 2-mercaptopyridine-1-oxide and flame atomic absorption spectroscopy is presented. The factors influencing extraction efficiency were evaluated, including the nature of the counter anion, pH of the sample solution, amount of ligand, flow rate of the sample and type of stripping solution. The maximum capacity of the membrane disk, modified by 10 mg of the ligand, was found to be 926 +/- 6 mu g of iron(III). The breakthrough volume was greater than 2500 ml. Iron(III) was completely recovered (> 99%) from water with a preconcentration factor of more than 166. The limit of detection of the proposed method was 0.63 ng ml(-1). The various cationic interferences had no effect on the recovery of iron(III) from the binary mixtures. The proposed method was applied to the determination of iron(III) from three different water samples.