Characterization of Oxide Interference for the Determination of Rare Earth Elements in Geological Samples by High Resolution ICP-MS
-
摘要: 电感耦合等离子体质谱(ICP-MS)用于测定稀土元素经常会引起M+、MO+、MOH+离子的质谱重叠干扰,其中制约分析准确度和精密度的主要因素是多原子离子干扰,尤其是轻稀土元素的氧化物和氢氧化物对重稀土元素的干扰,以及钡的7个天然同位素形成的氧化物和氢氧化物对轻稀土元素的干扰。本文采用高温高压密闭消解地质样品,高分辨电感耦合等离子体质谱法(ICP-MS)测定其中的痕量稀土元素,研究了低、中、高三种分辨率模式下氧化物的干扰情况,确定了最佳的测定同位素和合适的分辨率。分析结果表明,在低、中分辨率模式下,轻稀土元素Ce、Pr、Nd、Sm的氧化物和Ba的氧化物干扰明显,Gd元素的测定值严重偏离;在高分辨模式下,Ba氧化物对Eu的干扰以及大部分轻稀土元素氧化物对重稀土元素的干扰基本可以消除,无需进行校正,而只有157Gd受到141Pr16O的干扰突出,当样品中Pr/Gd的浓度比值大于100时,Gd的测量值必须进行数学校正。
-
关键词:
- 地质样品 /
- 稀土元素 /
- 高分辨电感耦合等离子体质谱法 /
- 氧化物干扰
Abstract: The main factor which limits the analysis accuracy and precision in the determination of rare earth elements (REEs) in geological samples is the interference of polyatomic ions, especially the interferences from oxide and hydroxide of light rare earth elements and natural Ba isotopes. A method for the determination of REEs in geological samples has been developed by using high temperature and pressure digestion and performing measurements using High Resolution Inductively Coupled Plasma-Mass Spectrometry (HR-ICP-MS). The oxide interferences were studied under low, moderate and high resolution modes, in order to select the best measured isotopes and appropriate resolution. The results show that oxides of light rare earth elements Ce, Pr, Nd, Sm and Ba oxide will produce interferences under low or middle resolution modes, and the value of Gd is seriously deviated. Under high resolution mode, the interference from 157Gd cannot be eliminated completely. When the Pr/Gd ratio is greater than 100, the value of Gd must be mathematically corrected. Meanwhile, interference corrections are unnecessary for light REEs oxide and hydroxide on heavy REEs and Ba on Eu. -
-
表 1 ICP-MS仪器的工作参数
Table 1. Working parameters for HR-ICP-MS instrument
工作参数 设定条件 提取电压 -1979 V 冷却气流速 16.01 L/min 辅助气流速 0.91 L/min 样品载气流速 1.013 L/min 蠕动泵转速 5.28 r/min 射频功率 1251 W 采样深度 -2.5 mm 采样锥孔径 1.1 mm 截取锥孔径 0.8 mm 每个质量数采样点 15个 表 2 方法检出限
Table 2. The detection limits of the method
测定元素 空白平均值(计数)s/cps 标准偏差(计数)δ/cps 检出限/(μg·g-1) Y 516343.1 2065.4 0.0040 La 698464.6 4343.2 0.0062 Ce 1391579.0 195515.1 0.14 Pr 763188.0 1425.5 0.0019 Nd 120353.0 1167.4 0.0097 Sm 102827.7 183.4 0.0018 Eu 392293.3 315.4 0.00080 Gd 123074.6 425.5 0.0035 Tb 687461.4 471.3 0.00069 Dy 219052.9 249.3 0.0011 Ho 873367.7 498.6 0.00057 Er 290162.2 490.6 0.0017 Tm 877120.5 426.1 0.00049 Yb 194294.5 175.7 0.00090 Lu 831246.0 408.7 0.00049 表 3 稀土元素测定中的质谱干扰[10]
Table 3. Spectroscopic interferences during the determination of REE by ICP-MS
稀土元素 质量数 丰度值/% 质谱干扰 La 138 0.09 138Ce,138Ba 139 99.91 - Ce 136 0.185 136Ba 138 0.251 142Nd,138Ba 140 88.45 - 142 11.114 142Nd Pr 141 100 - Nd 142 27.2 142Ce 143 12.2 - 144 23.8 144Sm 145 8.3 - 146 17.2 130BaO 148 5.7 148Sm,132BaO() 150 5.6 150Sm,134BaO() Sm 144 3.07 144Nd 147 14.99 130BaOH 148 11.24 148Nd,132BaO 149 13.82 132BaOH 150 7.38 150Nd,134BaO 152 26.75 152Gd, 136CeO, 136BaO, 135BaOH 154 22.75 154Gd, 142NdO, 138CeO, 138BaO, 137BaOH Eu 151 47.81 135BaO, 134BaOH 153 52.19 137BaO, 136BaOH Gd 152 0.2 152Sm, 136CeO, 136BaO, 135BaOH 154 2.18 154Sm, 138BaO, 137BaOH, 142NdO, 138CeO 155 14.8 138BaOH, 139LaO 156 20.47 156Dy, 140CeO 157 15.65 141PrO 158 24.84 158Dy, 142CeO, 142NdO 160 21.86 160Dy, 144SmO, 144NdO Tb 159 100 143NdO Dy 156 0.06 156Gd, 140CeO 158 0.1 158Gd, 142CeO, 142NdO 160 2.34 160Gd, 144NdO, 144SmO 161 18.91 145NdO 162 25.51 162Er, 146NdO 163 24.9 147SmO 164 28.18 164Er, 148SmO, 148NdO Ho 165 100 149SmO Er 162 0.14 162Dy, 146NdO 164 1.61 164Dy, 148SmO, 148NdO 166 33.61 150SmO, 150NdO 167 22.93 151EuO 168 26.78 168Yb, 152SmO, 152GdO 170 14.93 170Yb, 154GdO, 154SmO Tm 169 100 153EuO Yb 168 0.13 168Er, 152GdO, 152SmO 170 3.04 170Er, 154GdO, 154SmO 171 14.28 155GdO 172 21.83 156DyO, 156GdO 173 16.13 157GdO 174 31.83 174Hf, 158DyO, 158GdO 176 12.76 176Lu, 176Hf, 160GdO, 160DyO Lu 175 97.41 159TbO 176 2.59 176Yb, 176Hf, 160GdO, 160DyO 表 4 单一轻稀土元素的氧化物对重稀土元素的干扰
Table 4. Interference of single LREEs on HREEs determination
干扰元素
(浓度为200 μg/L)分辨率 干扰相当分析元素浓度 ρ/(μg·L -1) 157Gd 159Tb 163Dy 165Ho 166Er 169Tm 172Yb 175Lu La LR 0.255 0.002 0.002 0.001 0.002 0.001 0.001 0.001 MR 0.272 0.001 0.002 0.001 0.001 0 0.001 0.001 HR 0.046 0.001 0.003 0.001 0.002 0.001 0.001 0.001 Ce LR 1.091 0.035 0.004 0.001 0.004 0.001 0.007 0.001 MR 1.38 0.035 0.005 0.001 0.004 0.001 0.001 0.001 HR 0.21 0.008 0.002 0.001 0.002 0.001 0.001 0.001 Pr LR 78.904 0.038 0.001 0.001 0.002 0 0.001 0.001 MR 75.634 0.029 0.002 0 0.001 0.001 0 0.001 HR 0.087 0.001 0 0.001 0.001 0 0.001 0.001 Nd LR 0.081 2.283 0.125 0.027 3.134 0.019 0.019 0.019 MR 0.082 2.043 0.12 0.024 3.143 0.019 0.021 0.018 HR 0.014 0.339 0.07 0.017 2.1 0.017 0.019 0.019 Sm LR 0.045 0.031 1.626 0.42 0.646 0.053 0.035 0.031 MR 0.035 0.03 1.421 0.363 0.607 0.045 0.035 0.029 HR 0.031 0.034 0.114 0.032 0.057 0.035 0.034 0.029 干扰元素
(浓度为500 μg/L)分辨率 干扰相当分析元素浓度ρ/(μg·L-1) 157Gd 159Tb 163Dy 165Ho 166Er 169Tm 172Yb 175Lu La LR 0.492 0.003 0.004 0.001 0.004 0.001 0.002 0.001 MR 0.551 0.002 0.004 0.001 0.003 0.001 0.001 0 HR 0.059 0.001 0.003 0.001 0.002 0.001 0.001 0.001 Ce LR 2.784 0.088 0.006 0.001 0.007 0.001 0.015 0.001 MR 3.905 0.078 0.008 0.001 0.006 0.001 0.001 0.001 HR 0.82 0.027 0.007 0.001 0.002 0.001 0.002 0 Pr LR 184.293 0.087 0.001 0.001 0.002 0.001 0.002 0.001 MR 182.641 0.066 0.001 0.001 0.002 0.001 0.001 0.001 HR 4.189 0.005 0.002 0.001 0.001 0.001 0 0.001 Nd LR 0.136 4.655 0.222 0.018 6.31 0.001 0.003 0.002 MR 0.148 3.612 0.185 0.018 6.412 0.001 0.002 0.002 HR 0.002 0.051 0.102 0.006 1.134 0.001 0.003 0.002 Sm LR 0.03 0.002 2.976 0.725 1.186 0.043 0.013 0.001 MR 0.029 0.001 2.712 0.733 1.224 0.04 0.009 0.001 HR 0.005 0 0.991 0.076 0.224 0.024 0.001 0.001 表 5 稀土元素Gd测定中的主要质谱干扰
Table 5. The natural Gd isotopes and possible spectral inter-ferences
Gd的
质量数同位素
丰度/%质谱干扰(同位素丰度) 152 0.2 152Sm(26.7%) 154 2.2 152Sm(22.8%) 155 14.9 139La 16O(99.7%) 156 20.6 156Dy(0.06%), 140Ce 16O(88.3%) 157 15.7 141PrO(99.8%) 158 24.7 158Dy (0.1%), 142Ce 16O(11.1%), 142Nd(27.1%) 160 21.7 160Dy (2.3%), 144Nd 16O(23.8%),
144Sm 16O(30.9%)表 6 Ba及轻稀土氧化物干扰产率
Table 6. The yield of MO+/M+
MO+/M+ 产率/% LaO/La 2.50 NdO/Nd 3.02 CeO/Ce 2.78 SmO/Sm 0.96 PrO/Pr 3.58 BaO/Ba 0.11 表 7 不同浓度Ba对0.2 μg/L Eu的干扰及校正
Table 7. Interference of different concentration of Ba on 0.2 μg/L Eu
加入Ba的浓度
ρ(Ba)/(μg·L-1)Ba和Eu的
浓度比值
ρ(Ba)/ ρ(Eu)Eu的测定值
ρ(153Eu)/(μg·L-1)低分辨率 中分辨率 高分辨率 50 250 0.238 0.199 0.186 100 500 0.294 0.213 0.184 500 2500 0.842 0.489 0.198 表 8 不同浓度Eu受500 μg/L Ba的干扰及校正
Table 8. Interference of 500 μg/L Ba on different concentration of Eu
加入Eu的浓度
ρ(Eu)/(μg·L -1)Ba和Eu的
浓度比值
ρ(Ba)/ ρ(Eu)Eu的测定值
ρ(153Eu)/(μg·L-1)低分辨率 中分辨率 高分辨率 0.05 10000 0.546 0.374 0.057 0.1 5000 0.632 0.436 0.095 0.2 2500 0.727 0.447 0.200 0.4 1250 1.054 0.627 0.374 0.5 1000 1.202 0.716 0.483 5.0 100 6.061 4.958 4.632 表 9 标准物质中Ba氧化物对Eu的干扰
Table 9. Interferences of Ba-oxide on Eu in standard samples
标准物质
编号Ba的含量(n=5) 153Eu的含量(高分辨,n=5) w(Ba)/
(μg·g-1)RSD/% w(Eu)/
(μg·g-1)标准值 RSD/% GBW 07402 920 1.1 2.847 3.0 5.1 GBW 07403 1295 1.2 0.694 0.72 3.6 GBW 07408 488 1.7 0.965 1.20 19.6 GBW 07121 1153 1.1 0.858 1.00 14.2 表 10 稀土元素测定同位素和分辨率的选择
Table 10. Selection of determination isotopes and resolution for REEs measurements
测定
元素优选的
质荷比m/z同位素
丰度/%选用
分辨率Y 89 100 LR La 139 100 LR Ce 140 100 LR Pr 141 100 LR Nd 146 17.2 LR Sm 147 15 LR Eu 153 52.2 HR Gd 157 15.7 HR Tb 159 100 HR Dy 163 24.9 HR Ho 165 100 HR Er 166 33.6 HR Tm 169 100 LR Yb 172 21.9 LR Lu 175 97.4 LR -
[1] 王中刚,赵振华.稀土元素地球化学[M].北京:科学出版社,1989: 88-94.
[2] 王君玉,吴葆存,李志伟,韩敏,钟莅湘.敞口酸溶-电感耦合等离子体质谱法同时测定地质样品中45个元素[J].岩矿测试,2011,30(4):440-445. http://www.cnki.com.cn/Article/CJFDTOTAL-YKCS201104013.htm
[3] 周国兴,刘玺祥,崔德松.碱熔ICP-MS法测定岩石样品中稀土等28种金属元素[J].质谱学报,2010,31(2):120-124. http://www.cnki.com.cn/Article/CJFDTOTAL-ZPXB201002014.htm
[4] 陈永欣,黎香荣,韦新红,吕泽娥,谢毓群,蔡维专.微波消解-电感耦合等离子体质谱法测定土壤和沉积物中痕量稀土元素[J].岩矿测试,2011,30(5):560-565. http://www.cnki.com.cn/Article/CJFDTOTAL-YKCS201105009.htm
[5] 李冰,尹明.电感耦合等离子体质谱法测定生物样品中超痕量稀土元素时氧化物干扰对研究[J].岩矿测试,2000,19(2):101-103. http://www.cnki.com.cn/Article/CJFDTOTAL-YKCS200002004.htm
[6] 曹淑琴,陈杭亭,曾宪津.电感耦合等离子体质谱法测定生物样品中稀土元素[J].分析化学,1999,27(6):621-625. http://www.cnki.com.cn/Article/CJFDTOTAL-FXHX199906000.htm
[7] 尹明,李冰.感耦等离子体质谱法在高纯稀土氧化物分析中的基体谱线干扰的研究[J].岩矿测试,1994,13(2): 81-91. http://www.cnki.com.cn/Article/CJFDTOTAL-YKCS402.000.htm
[8] 白金峰,张勤,孙晓玲,董永胜,范辉,徐进力,刘亚轩.高分辨电感耦等离子体质谱法测定地球化学样品中钪钇和稀土元素[J].岩矿测试,2011,30(1):17-22. http://www.cnki.com.cn/Article/CJFDTOTAL-YKCS201101007.htm
[9] Reed N M, Cairns R O, Hutton R C. Characterization of polyatomic ion interferences in inductively coupled plasma mass spectrometry using a high resolution mass spectrometer [J].Analytical Atomic Spectrometry,1994,9(8):881-896. doi: 10.1039/ja9940900881
[10] Raut N M, Huang L S, Aggarwal S K. Uncertainty propagation through correction methodology for the determination of rare earth elements by quadrupole based inductively coupled plasma mass spectrometry [J]. Analytica Chimica Acta,2005, 530:91-103. doi: 10.1016/j.aca.2004.08.067
[11] Longerich H P, Fryer B J, Strong D F, Kantipuly C J. Effects of operating conditions on the determination of the rare earth elements by inductively coupled plasma-mass spectrometry (ICP-MS) [J]. Spectrechimica Acta: Part B, 1987, 42:75-78. doi: 10.1016/0584-8547(87)80051-4
[12] Vaughan M A, Horlick G, Samantha H T. Effect of operating parameters on analyte signals in inductively coupled plasma mass spectrometry [J]. Analytical Atomic Spectrometry, 1987, 2:765-772. doi: 10.1039/ja9870200765
[13] Vaughan M A, Horlick G. Effect of sampler and skimmer orifice size on analyte and analyte oxide signals in inductively coupled plasma-mass spectrometry [J]. Spe-ctrochimica Acta: Part B,1990,45(12):1289-1299. doi: 10.1016/0584-8547(90)80183-J
[14] Tan S H, Horlick G. Matrix-effect observations in in-ductively coupled plasma mass spectrometry [J].Analytical Atomic Spectrometry, 1987, 2:745-763. doi: 10.1039/ja9870200745
[15] Tan S H, Horlick G. Background spectral features in inductively coupled plasma/mass spectrometry [J].Applied Spectroscopy, 1986, 40:445-460. doi: 10.1366/0003702864508944
[16] Gray A l, Williams J G. Oxide and doubly charged ion response of a commercial inductively coupled plasma mass spectrometry instrument[J]. Analytical Atomic Spectrometry, 1987, 2:599-606. doi: 10.1039/ja9870200599
[17] Shibata N, Fudagawa N, Kubota M. Effects of hydrogen mixed with argon carrier gas in electrothermal vaporization-inductively coupled plasma-mass spectro-metry [J]. Spectrochimic Acta: Part B, 1992, 47(4):505-516. doi: 10.1016/0584-8547(92)80043-G
[18] Kawabata K, Kishi Y, Kawaguchi O, Watanabe Y, Inoue Y. Determination of rare-earth elements by inductively coupled plasma mass spectrometry with ion chromatography [J].Analytical Chemistry,1991,63(19):2137-2140. doi: 10.1021/ac00019a013
[19] Jarvis K E, Gray A L, Mccurdy E.Avoidance of spectral interference on Eu in inductively coupled plasma mass spectrometry by sensitive measurement of double charged ions[J].Analytical Atomic Spectrometry,1989,4:743-747. doi: 10.1039/ja9890400743
[20] Annette Behrens. Determination of gadolinium in geological samples by inductively coupled plasma mass spectrometry and multivariate calibration [J]. Spectrochimica Acta: Part B, 1995, 50:1521-1530. doi: 10.1016/0584-8547(95)01362-8
[21] 胡圣虹,林守麟,刘勇胜,高山.等离子体质谱法测定地质样品中痕量稀土元素的基体效应及多原子离子干扰的校正研究[J].高等学校化学学报,2000,19(2):368-372. http://www.cnki.com.cn/Article/CJFDTOTAL-GDXH200003009.htm
[22] Smirnova E V, Mysovskaya I N, Lozhkin V I, Sandimirova G P, Pakhomova N N, Smagunova A A. Spectral interference from polyatomic barium ions in inductively coupled plasma mass spectrometry[J].Journal of Applied Spectroscopy, 2006, 73(6):911-917. doi: 10.1007/s10812-006-0175-0
-