微波消解-电感耦合等离子体质谱法测定煤飞灰中14种金属元素

使用HNO₃-HF混合酸体系微波消解煤飞灰样品,建立了电感耦合等离子体质谱法(ICP-MS)测定煤飞灰中14种痕量元素含量的分析方法。样品微波消解的程序为:0.2 g样品中加入10 mL HNO₃和5 mL HF,5 min加热到110 ℃保持5 min、5 min升温到150 ℃保持5 min、5 min升至190 ℃恒温30 min。实验对较高浓度元素Be、Co、Cr、Cu、Mn、Mo、Ni、Pb、Sn、V和Zn采取稀释10倍、降低总溶解性固体(TDS)含量后以外标法进行测定,Cd、Sb、Tl等低含量元素则采用标准加入法以消除基体干扰;方法检出限为0.001~0.04 mg/kg。将实验方法应用于煤飞灰标准物质SRM 1633c中11种金属元素(Be、Cd、Co、Cr、Cu、Mn、Ni、Pb、Sb、V、Zn)的测定,结果与认定值基本一致,相对标准偏差(RSD,n=6)为0.3%~3.6%,加标回收率在83%~112%之间。采用实验方法测定煤飞灰实际样品的结果与12个实验室采用电感耦合等离子体原子发射光谱法(ICP-AES)、ICP-MS、原子吸收光谱法(AAS)、X射线荧光光谱法(XRF)和滴定法等其他方法测得结果的平均值对比,经t检验统计表明无显著性差异。

Determination of fourteen metal elements in coal fly ash by inductively coupled plasma mass spectrometry with microwave digestion

The coal fly ash sample was treated by microwave digestion in HNO₃-HF mixed acid system. A determination method of fourteen trace elements in coal fly ash by inductively coupled plasma mass spectrometry(ICP-MS) was established. The microwave digestion procedures for sample were as follows: 10 mL of HNO₃ and 5 mL of HF were added into 0.2 g of sample; the temperature was increased to 110 ℃ within 5 min and kept for 5 min; then, the temperature was increased to 150 ℃ within 5 min and kept for 5 min; finally, the temperature was increased to 190 ℃ within 5 min and kept for 30 min. The elements with high content such as Be, Co, Cr, Cu, Mn, Mo, Ni, Pb, Sn, V and Zn were diluted for 10 times to reduce the content of total dissolved solid(TDS) followed by determination with external standard method. For the elements with low content such as Cd, Sb and Tl, the standard addition method was adopted to eliminate the matrix interference. The detection limit of method was 0.001-0.04 mg/kg. The proposed method was applied to the determination of eleven metal elements (Be, Cd, Co, Cr, Cu, Mn, Ni, Pb, Sb, V, Zn) in certified reference material of coal fly ash (SRM 1633c), and the results were consistent with the certified values. The relative standard deviations(RSD,n=6) were between 0.3% and 3.6%. The recoveries were between 83% and 112%. The determination results of coal fly ash actual sample according to the experimental method were compared with the average values obtained by inductively coupled plasma atomic emission spectrometry(ICP-AES), ICP-MS, atomic absorption spectrometry(AAS), X-ray fluorescence spectrometry(XRF) and titration method in 12 laboratories. The t test statistics indicated that there was no significant difference.