Abstract：The sample was dissolved with nitric acid. After separation with cation-exchange resin, trace arsenic in high purity indium was determined by graphite furnace atomic absorption spectrometry. The optimum conditions of sample dissolution, ion-exchange separation and determination of arsenic were investigated. The results showed that, 0.4 g of indium could be dissolved completely in 5 mL of nitric acid. After ion exchange with 0.4 mol/L nitric acid as leacheate, trace aluminium, iron, tin, copper, lead, zinc, cadmium, magnesium, thallium, silver, nickel and most of indium in the sample could be separated and removed. Although silicon could not be separated with arsenic, it had no influence on the determination. As the sampling amount was 20 μL, the linear range of this method was 5-35 ng/mL, the detection limit was 0.8 ng/mL, and the lower limit of quantitation was 0.02 μg/g, which was one order of magnitude lower than 0.3 μg/g in industry standard method YS/T 230.3-1994. The proposed method was applied to the analysis of actual sample, and the results were consistent with those obtained by inductively coupled plasma mass spectrometry (ICP-MS). The relative standard deviation (RSD, n=8) was 1.7 %-15.7 %, and the recoveries were 95 %-110 %.
