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    高压密闭消解-电感耦合等离子体质谱法测定钨矿石和钼矿石中银的含量

    Determination of Silver in Tungsten Ore and Molybdenum Ore by Inductively Coupled Plasma Mass Spectrometry with High Pressure Closed Digestion

    • 摘要: 针对现行标准方法GB/T 14352.12—2010中火焰原子吸收光谱法难以满足低含量银的检测需求,提出了题示研究。取0.100 0 g钨矿石或钼矿石样品,用3 mL氢氟酸和1 mL硝酸于180 ℃密闭消解12 h,冷却后在150 ℃电热板上加热赶酸至白烟冒尽,加入1 mL硝酸蒸发至干,再加入1 mL硝酸和3 mL水,于150 ℃密闭加热10 h。冷却后将溶液转移至100 mL比色管中,用2%(体积分数)硝酸溶液定容,在动能歧视碰撞模式、碰撞气氦气流量6.0 mL·min−1、雾化气流量0.85 L·min−1、射频功率1 550 W的条件下采用电感耦合等离子体质谱法(ICP-MS)测定溶液中银的含量,选用铑为内标进行在线校正。结果表明,银的质量浓度在100.0 μg·L−1以内和对应的信号强度呈线性关系,检出限(3s)为0.008 μg·g−1。方法用于分析国家一级标准物质,得到的测定值与认定值基本一致,测定值的相对标准偏差(n=12)为1.3%~3.8%。对实际样品进行加标回收试验,回收率为94.0%~105%。

       

      Abstract: As the current standard method of flame atomic absorption spectrometry in GB/T 14352.12—2010 was difficult to meet the detection requirements of low content silver, the study mentioned by the title was proposed. 0.100 0 g of tungsten or molybdenum ore sample was taken, and digested with 3 mL of hydrofluoric acid and 1 mL of nitric acid at 180 ℃ for 12 h in a sealed environment. After cooling, the solution was heated on a electric heating plate at 150 ℃ to remove the acid until white smoke was emitted, and then 1 mL of nitric acid was added. The mixture was evaporated to dryness, and 1 mL of nitric acid and 3 mL of water were added. The solution was heated in a sealed environment at 150 ℃ for 10 h. After cooling, the solution was transferred to a 100 mL-colorimetric tube, and made its volume up to 100 mL with 2% (volume fraction) nitric acid solution. Silver in the solution was determined by inductively coupled plasma mass spectrometry(ICP-MS) under the condition of kinetic energy discrimination collision mode, collision gas helium flow rate of 6.0 mL·min−1, atomization gas flow rate of 0.85 L·min−1, and radio frequency power of 1 550 W, and rhodium was selected as the internal standard for online calibration. As shown by the results, linear relationship between the mass concentration of silver and the corresponding signal intensity was found within 100.0 μg·L−1, with detection limit (3s) of 0.008 μg·L−1. This method was applied to the analysis of national first-class certified reference materials, and the determined values were basically consistent with the certified values, with RSDs of the determined values (n=12) in the range of 1.3%-3.8%. Test of recovery was made on the actual samples by the standard addition method, giving results in the range of 94.0%-105%.

       

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