HG-AFS Determination of Arsenic in Iron Ore with Microwave Assisted Sample Digestion

HG-AFS was applied to the determination of arsenic in iron ore.The sample was digested in a microwave sample digestor under the optimized conditions of: ① power for digestion: 650 V;② raising the digestion temperature to 170 ℃ at a rate of 5 ℃·min-1,and keeping for 20 min;and ③ cooling for 20 min.Definite amounts of sat′d boric acid solution and solutions of thiourea and ascorbic acid were added to the sample solution as complexing agents.The sample solution was diluted to 50 mL and used for HG-AFS determination of arsenic under the working condition of the instrument.The preset volumes of injection of sample solution and 10 g·L-1 KBH4 solution were 1.0 mL and 0.5 mL respectively.Definite amount of iron solutions were added to each of the test solutions in the preparation of standard curve in order to match the matrix inteference of iron.Linear relationship between values of fluorescence intensity and mass concentration of arsenic was obtained in the range from 0.90 to 100 μg·L-1,and detection limit (3s) found for the method was 0.40 μg·L-1.The proposed method was applied to the determination of arsenic in standard samples of iron ore,giving results in consistency with the standard values.