ICP-MS测定土壤重金属元素消解方式的探索

为改进湿法消解有机质含量偏高土壤样品的方法,通过电感耦合等离子体质谱(IC P-M S)对比了双氧水-氢氟酸-硝酸(H2 O2-HF-HNO3)、盐酸-硝酸-氢氟酸(HCl-HNO3-HF)、王水-逆王水-硝酸-氢氟酸(NO2 Cl-H2[(N3 O8)Cl]-HNO3-HF)、双氧水-盐酸-硝酸-氢氟酸(H2 O2-...

Exploration of Digestion Method for Determination of Heavy Metal Elements in Soil by ICP-MS

In order to improve the wet digestion of soil samples with high organic matter content, this paper by ICP-MS compared to analyze Copper (Cu), Chromium (Cr), Lead (Pb), Cadmium (Cd), Nickel (Ni) and Zinc (zinc) in national soil component analysis standard materials (GSS-1a-GSS-8a) by five different digestion systems, and they were the H₂O₂-HF-HNO₃, HCl-HNO₃-HF, HNO₃·3HCl-3HNO₃·HCl-HNO₃-HF, H₂O₂-HCl-HNO₃-HF and LOI-HNO₃-HF. 103Rh was used as the internal standard element in the determination of ICP-MS，and the appropriate monitoring mode was selected for different determination elements. The results showed that the digestion effect of Cu, Cr, Pb, Cd, Ni and Zn was the best when setting the heating rate of 3 ℃·min-1, calcining at 550 ℃ for 3 h, and then digesting with nitric acid and hydrofluoric acid after cooling. The results of standard addition recovery experiment shown that there was no significant difference between the measured value and the standard value of the standard substance. The recovery rate of standard addition is 91%~105%, which shown that the accuracy and precision of this method met the requirements. In the hydrogen peroxide-hydrofluoric acid-nitric acid system and hydrogen peroxide-hydrochloric acid-nitric acid-hydrofluoric acid system, the decomposition of hydrogen peroxide is severe when heated, and the digestion solution is easy to splash, resulting in low test results. The test results of hydrochloric acid-nitric acid-hydrofluoric acid system and aqua regia-aqua regia-nitric acid-hydrofluoric acid digestion system are not stable, which may be due to the interference of Cl- on the mass spectrum of the instrument, and in the open system, CrO₂Cl₁₂ is easy to volatilize during the sample decomposition process, resulting in low Cr content. At the same time, the above methods are also applied to the comparative analysis of soil samples with high organic matter collected from the peat land of Lake Dajiuhu. The result shown that the digestion method of loss on ignition-nitric acid-hydrofluoric acid digestion system was more thorough, with less acid addition, less interference and stable test results, so this method was suitable for digestion of large quantities of samples with high organic matter content.