Determination of Arsenic in Tungsten and Molybdenum Ores by Hydride Generation-Atomic Fluorescence Spectrometry with Hydrochloric Acid-Nitric Acid Water-bath Digestion
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摘要:
应用氢化物发生原子荧光光谱法(HG-AFS)测定钨矿石和钼矿石中的砷, 钨钼铜铅锌铋镉等共存元素在不经分离或不加掩蔽剂的情况下对砷测定产生严重干扰。本文采用盐酸-硝酸(5 : 1) 水浴加热分解样品, 加入柠檬酸-碘化钾掩蔽共存元素, 促进这些元素还原成低价离子或者直接形成沉淀以消除干扰; 再加入硫脲-抗坏血酸还原后直接用HG-AFS测定砷量。砷的检出限为0.014 μg/g, 测定范围为0.2~2000 μg/g, 方法精密度为0.7%~7.5%, 加标回收率为92.3%~102.9%。本方法与国家标准方法相比, 检出限低, 检测范围宽, 干扰元素不经分离可直接测定砷的含量。
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关键词:
- 钨矿石 /
- 钼矿石 /
- 砷 /
- 盐酸-硝酸水浴加热 /
- 氢化物发生原子荧光光谱法
Abstract:Determining arsenic in tungsten and molybdenum ores using Hydride Generation-Atomic Fluorescence Spectrometry (HG-AFS) without separation and a screening agent commonly suffer from the interferences of associated elements such as W, Mo, Cu, Pb, Zn, Bi and Cd. In this study, the samples were digested by hydrochloric acid-nitric acid (volume ratio of 5 : 1) in a water bath. Citric acid and potassium iodide solution were used to screen interferences of associated elements by reducing these elements to low valences or forming the precipitates. Lastly thiourea-ascorbic acid solution was added and As content was determined directly by HG-AFS. The method yields an As detection limit of 0.014 μg/g, precision of 0.7%-7.5%, and recovery of 92.3%-102.9%. Compared to the national standard method, this method has the advantages of low detection limit, wide detection ranges, and direct determination without separating interference elements.
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表 1 方法精密度实验结果
Table 1. Precision and accuracy tests of the method
样品编号 As含量(μg/g) 相对误差
(%)RSD
(%)测定平均值 标准值 HWM-1 18.0 - - 2.7 HWM-2 263 - - 1.7 HWM-3 113 - - 2.5 HWM-4 44.8 - - 3.0 GBW07238 1.61 1.6 0.63 5.2 GBW07239 1.01 1.0 1.00 7.5 GBW07285 17.8 18.8 -5.32 3.0 GMo-1 5.17 5.2 -0.58 2.6 GMo-3 4.63 4.7 -1.49 2.6 GBW07241 70.8 69.9 1.29 3.5 GBW07240 1811 1800 0.61 0.7 
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表 2 钼矿石和钼矿石加标回收实验结果
Table 2. Spiked recovery of the method
样品 As本底值
(ng/mL)As加入量
(ng/mL)As测定值
(ng/mL)As回收率
(%)As加入量
(ng/mL)As测定值
(ng/mL)As回收率
(%)GBW07238 3.16 3 6.231 102.4 6 8.698 92.3 GBW07239 2.096 2 4.03 96.7 4 6.212 102.9 GBW07240 3632.4 3000 6660 100.9 6000 9525.8 98.2 GBW07241 137.96 100 230.73 92.8 200 330 96.0 GBW07285 34.98 40 72.56 94.0 80 112.66 97.1 GMo-1 10.277 10 19.694 94.2 20 30.71 102.2 GMo-3 9.52 10 19.255 97.4 20 29.156 98.2
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[1] [2] [3] [4] [5] doi: 10.1021/cr00094a002
[6] [7] doi: 10.1039/b917755h
[8] [9] [10] [11] [12] [13] [14] [15] [16] -
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