Determination of Silver in Samples for Geochemical Exploration by Inductively Coupled Plasma-Mass Spectrometry after Ammonia Complexation
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摘要:
应用电感耦合等离子体质谱法(ICP-MS)测定化探样品中的Ag时, 两个同位素107Ag和109Ag分别受90Zr16O1H、91Zr16O和92Zr16O1H、93Nb16O等的干扰, 即使采用干扰系数法校正, 测定结果误差仍较大。本文采用硝酸-氢氟酸-高氯酸封闭分解样品, 氨水沉淀分离干扰元素Zr后以103Rh为内标用ICP-MS测定, 溶液中残留Zr对107Ag的测定干扰采用干扰系数法进行校正。方法检出限(3σ)为4.1 ng/g, 相对标准偏差(n=12) 为2.5%~7.8%。经53个地球化学标准物质验证, 溶液中的Ag未见损失。本方法是在氨性介质中Ag与氨形成稳定的络合离子, 而Zr则生成氢氧化物沉淀, 实现了Ag和Zr的分离, 大大减小了Zr对Ag的测定干扰; 采用封闭分解样品, 减少用酸量, 降低了样品空白值, 操作方法比高压密闭分解和P507萃淋树脂分离方法更简便快速。
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关键词:
- 化探样品 /
- 银 /
- 氨水 /
- 封闭溶样 /
- 电感耦合等离子体质谱法
Abstract:Isobaric ions interfere with two isotopes of Ag during determination by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS), i.e., 90Zr16O1H and 91Zr16O on 107Ag, and 92Zr16O1H and 93Nb16O on 109Ag. Although an interference correction coefficient method was used for the calibration of the analytical results, the analytical errors remain serious. In the proposed method, samples were closed decomposed by nitric acid, hydrofluoric acid, and perchloric acid. Ammonia was used to precipitate Zr and the purified Ag was determined by ICP-MS using 103Rh as the internal standard. The interference caused by the residual Zr was calibrated by the interference coefficient method. The method has a detection limit (3σ) of 4.1 ng/g and relative standard deviation (n=12) ranging from 2.5% to 7.8%. Determination of Ag in 53 primary certified materials of geochemical exploration indicates no loss of Ag. Using ammonium as the reagent, separation of Zr and Ag was successfully achieved due to the formation of the stable Ag-ammonium complex and Zr-hydroxide precipitate. The separation of Ag from Zr has reduced the interferences of Zr on Ag. Compared with the high-pressure sealed decomposition method and the P507 extraction resin separation method, the closed sample decomposition method is much simpler with less acid used and a lower blank.
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表 1 方法精密度
Table 1. Precision tests of the method
标准物质
编号Ag含量(μg/g) RSD
(%)12次测定值 平均值 GBW07308
(水系沉积物)0.057 0.054 0.059 0.064 0.059 0.051
0.058 0.057 0.052 0.060 0.054 0.0660.058 7.8 GBW07318
(水系沉积物)0.134 0.142 0.126 0.145 0.137 0.122
0.146 0.153 0.141 0.149 0.140 0.1310.139 6.7 GBW07360
(水系沉积物)0.737 0.762 0.755 0.742 0.777 0.786
0.724 0.731 0.754 0.767 0.736 0.7530.752 2.5 GBW07405
(土壤)4.49 4.5 84.20 4.58 4.17 4.45
4.63 4.29 4.52 4.29 4.55 4.534.44 3.6 
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表 2 标准物质分析结果
Table 2. Analytical results of Ag in certified reference materials
标准物质
编号Ag含量(μg/g) ΔlgC 标准物质
编号Ag含量(μg/g) ΔlgC 标准值 测定值 标准值 测定值 GBW07304 0.084 0.092 0.040 GBW07403 0.091 0.086 0.025 GBW07305 0.36 0.377 0.020 GBW07404 0.070 0.064 0.039 GBW07306 0.36 0.372 0.014 GBW07405 4.4 4.43 0.003 GBW07307 1.05 1.12 0.028 GBW07406 0.20 0.213 0.027 GBW07308 0.062 0.055 0.052 GBW07407 0.057 0.056 0.008 GBW07309 0.089 0.083 0.030 GBW07408 0.060 0.057 0.022 GBW07310 0.27 0.284 0.022 GBW07423 0.076 0.078 0.011 GBW07311 3.2 3.31 0.015 GBW07424 0.083 0.090 0.035 GBW07312 1.15 1.24 0.033 GBW07425 0.098 0.111 0.054 GBW07317 0.027 0.033 0.087 GBW07426 0.078 0.086 0.042 GBW07318 0.13 0.146 0.050 GBW07427 0.067 0.063 0.027 GBW07358 0.14 0.146 0.018 GBW07428 0.084 0.085 0.005 GBW07359 0.050 0.045 0.046 GBW07429 0.15 0.166 0.044 GBW07360 0.74 0.772 0.018 GBW07430 0.14 0.157 0.050 GBW07361 0.044 0.038 0.064 GBW07446 0.050 0.050 0.000 GBW07362 0.092 0.085 0.034 GBW07447 0.066 0.065 0.007 GBW07363 0.082 0.080 0.011 GBW07448 0.050 0.057 0.057 GBW07364 0.14 0.142 0.006 GBW07449 0.068 0.068 0.000 GBW07365 0.068 0.063 0.033 GBW07450 0.073 0.082 0.050 GBW07301a 0.036 0.034 0.025 GBW07451 0.074 0.086 0.065 GBW07302a 0.040 0.034 0.071 GBW07452 0.069 0.076 0.042 GBW07303a 0.20 0.217 0.035 GBW07453 0.092 0.102 0.045 GBW07304a 0.22 0.241 0.040 GBW07454 0.070 0.063 0.046 GBW07305a 0.63 0.657 0.018 GBW07455 0.070 0.070 0.000 GBW07307a 1.20 1.19 0.004 GBW07456 0.14 0.159 0.055 GBW07308a 0.12 0.122 0.007 GBW07457 0.13 0.137 0.023 GBW07402 0.054 0.048 0.051 注：ΔlgC=∣lgCi-lgCs∣，Ci为标准物质的测定值，Cs为标准物质的标准值。
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