浊点萃取-电感耦合等离子体质谱法测定地质样品中金

采用盐酸和硝酸溶解样品,加热蒸干硝酸后,控制萃取液中盐酸浓度为1.0mol/L左右,以5-巯基-3-苯基-1,3,4-噻二唑-2(3H)硫酮钾盐(铋试剂Ⅱ)为络合剂,聚乙二醇辛基苯基醚(Triton X-100)为萃取剂,在沸水浴中对金进行浊点萃取,建立了电感耦合等离子体质谱法(ICP-MS)测定地质样品中金的方法。浊点萃取的最佳条件为:在稀释后的样品溶液中加入0.5mL铋试剂Ⅱ溶液、2.5mL Triton X-100溶液后,将比色管置于100℃水浴锅中加热30min,使用体积比为10%的稀王水溶解有机相并定容到5mL。选择20μg/L185 Re为内标可有效校正铋试剂Ⅱ的基体效应和仪器的信号漂移。浊点萃取方法的富集比为4.75,方法检出限为1.3μg/L。采用方法对GBW07405黄红壤标准物质与GBW07300金矿石金成分分析标准物质、S1和S2实际岩石样品进行测定,结果与认定值或泡沫吸附-石墨炉原子吸收光谱法测定值一致,相对标准偏差(RSD,n=6)为1.2%~3.6%。

Determination of gold in geological sample by inductively coupled plasma mass spectrometry with cloud point extraction

After the sample was dissolved by hydrochloric acid and nitric acid, the nitric acid was dried by distillation and the hydrochloric acid in the extract solution was controlled at around 1.0 mol/L. With 5-mercapto-3-phenyl-1,3,4-thiadiazole-2(3H)-thione potassium salt (bismuth reagent Ⅱ) as complex agent and octyl phenoxy poly ethoxy (Triton X-100) as extraction agent, gold was extracted with cloud point extraction in boiling water bath. Thus, a method for determination of gold in geological sample was established by inductively coupled plasma mass spectrometry(ICP-MS). The optimal conditions for cloud point extraction were as follows: 0.5 mL of bismuth reagent Ⅱ, 2.5 mL of Triton X-100 solution was added in the diluted sample solution, the colorimetric tube was heated in water bath at 100 ℃ for 30 min and the organic phase was diluted to 5 mL with 10% (volume fraction) diluted aqua regia. The matrix effect of bismuth reagent Ⅱ and signal drift of instrument could be effectively corrected with 20 μg/L ¹⁸⁵Re as inner standard. The enrichment ratio of cloud point extraction was 4.75. The detection limit was 1.3 μg/L. GBW07405 yellow-red soil certified reference material, GBW07300 gold component analysis certified reference material for gold ores, S1 and S2 actual rock samples were determined by this method, whose results were consistent with the certified values or those obtained by foam adsorption-graphite furnace atomic absorption spectrometry. The relative standard deviation (RSD, n=6) was 1.2%-3.6%.