Determination of Major and Trace Elements in Geological Samples by Laser Ablation Inductively Coupled Plasma-Mass Spectrometry with Ammonium Fluoride Digestion
-
摘要:
准确测定岩石、土壤或矿物等地质样品中的关键金属元素含量，是开展关键金属矿产基础理论研究、探讨关键金属元素超常富集成矿机制、开展找矿勘查和绿色利用的重要前提。由于激光剥蚀电感耦合等离子体质谱（LA-ICP-MS）在整体元素分析方面具有高灵敏度、多原子离子干扰少、样品消耗少和前处理简单等优势，被认为是一种具有较大潜力的绿色地质分析技术。然而，天然地质样品的组成十分复杂多样，在使用LA-ICP-MS进行元素整体分析之前通常需要将其消解均一化，这些前处理流程不仅复杂、费时费力，并且需要使用大量浓酸，增加了样品丢失和污染的风险。本文提出了将氟化铵消解方法作为LA-ICP-MS整体元素分析前处理技术，利用氟化铵具有高沸点，能在常压条件下对难溶矿物进行化学分解的特点，可实现岩石中不同类型矿物的物理结构均质化和化学成分均匀化，形成超细粉末颗粒。氟化铵消解后的粉末可以直接进行粉末压片，通过加入In内标结合岩石参考物质外标校正，实现LA-ICP-MS快速多元素整体定量分析。通过重量法可以准确获得Si元素质量分数。通过对5个国际岩石标准物质的分析测试，整体分析测试精度优于5%，45个主微量元素（包括关键金属元素）分析准确度优于10%，表明了本方法的有效性和可靠性。本方法仅需要2h即可完成样品完全消解，可批量操作。相比于传统酸消解流程，新方法大幅降低无机酸的用量，具有绿色环保的特点。
Abstract:BACKGROUND The accurate determination of concentrations of key metal elements in geological samples (such as rocks, soils or ores) is an important foundation for the basic theory research of critical metal ores, supernormal enrichment mechanism of critical metal elements, mineral resource exploration and green utilization of mineral resources. Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) has advantages of providing adequate sensitivity, low interferences of polyatomic ions, small quantities of sample consumption and simple sample preparation. It is perceived as a green geological analytical technique with great potential in the whole elemental determination. However, the pretreatment of geological samples is the key factor limiting its pervasive application. The current bulk analysis of LA-ICP-MS is limited by the problem of sample homogenization. Most of the traditional pretreatment techniques are obtained by physical grinding, which has low efficiency and the risk of cross contamination. Therefore, new pre-processing techniques for geological samples need to be proposed to meet the requirements of LA-ICP-MS analysis.
OBJECTIVES To develop a new pre-treatment technology for geological samples and establish a rapid, efficient, green, and environment-friendly LA-ICP-MS elemental quantitative analysis technology.
METHODS The ammonium fluoride (NH4F) was used to digest five rock reference materials (BCR-2, BHVO-2, AGV-2, RGM-2, GSP-2). Ultrafine particulate powders obtained after evaporation and stirrer processes were directly pressed into tablets. The rapid whole elemental quantitative analysis of LA-ICP-MS can be achieved by adding the indium (In) internal standard and external standard correction of geological rock reference material. The digestion time of NH4F, the morphology, element composition, element distribution and other characteristics were also investigated. The mass fraction of SiO2 was evaluated to the total normalization 100% and gravimetric method.
RESULTS The results show that 2h digestion time can completely decompose geological rock samples. Moreover, the digestion products have the characteristics of ultrafine powder with a typical grain size of smaller than 5μm. Various silicate rocks after NH4F digestion have a consistent grain morphology and size, allowing the production of pressed powder pellets that have excellent cohesion and homogeneity suitable for laser ablation micro-analysis without the addition of a binder. The mass fraction of SiO2 in rock samples is obtained accurately using the gravimetric method. The analytical results of five reference materials generally agreed with the recommended values, with the analytical precision within 10% for 45 major and trace elements.
CONCLUSIONS A NH4F digestion method as sample preparation for the rapid determination of major and trace elements in silicate rock powders by LA-ICP-MS was introduced. The analytical results obtained for five rock reference materials generally agree with the recommended values within a relative deviation of <10%, confirming the usefulness of this method for quantitative elemental analysis of silicate rock samples. The applicability field of this method includes most common silicate rock samples. Furthermore, sediment, solid and ore can also be analyzed by the NH4F digestion method. There are many innovations for the new technique, including reducing matrix effects between reference materials and samples, spiking the internal standard simply and feasibly and sample batch processing. The optimized method can be used to quickly prepare compact tablet samples with high uniformity and without elements loss, which are suitable for LA-ICP-MS. This method only needs the use of NH4F solid reagent, which greatly reduces the consumption of other inorganics acids. Moreover, NH4F is a neutral reagent, which decreases the potential risk of acid reagent harmful in the pretreatment process to laboratory personnel, and has the added advantage of greener environmental protection, safety, and high efficiency.
-
-
图 1 不同岩石类型标准物质（BCR-2、BHVO-2、GSP-2、AGV-2和RGM-2）氟化铵消解产物的扫描电子显微镜（SEM）图像（a～e）；GSP-2消解产物的粉末压片表面微观特征和激光剥蚀坑图像（f）
Figure 1.
表 1 两种不同SiO2的定量计算方法所得到的平均值和相对误差
Table 1. The measured values and relative deviation （RD） of rock reference materials obtained from two different SiO2 quantitative correction schemes.
岩石标准物质
编号SiO2标准值
（%）方法一 方法二 SiO2测试平均值
（%）相对偏差
（%）SiO2测试平均值
（%）相对偏差
（%）BCR-2 54.1 56.4 4.3 54.0 −0.2 BHVO-2 49.9 47.4 −5.0 48.9 −2.0 GSP-2 66.6 62.8 −5.7 67.6 1.5 AGV-2 59.3 53.8 −9.3 59.4 0.2 RGM-2 73.4 67.9 −7.5 74.2 1.1 
下载: 导出CSV
-
[1] 李超, 王登红, 屈文俊, 等. 关键金属元素分析测试技术方法应用进展[J]. 岩矿测试, 2020, 39(5): 658−669.
Li C, Wang D H, Qu W J, et al. A review and perspective on analytical methods of critical metal elements[J]. Rock and Mineral Analysis, 2020, 39(5): 658−669.
[2] 刘勇胜, 屈文俊, 漆亮, 等. 中国岩矿分析测试研究进展与展望(2011—2020)[J]. 矿物岩石地球化学通报, 2021, 40(3): 515–539.
Liu Y S, Qu W J, Qi L, et al. Advances and perspective of reasearches on rock and mineral analyses in China (2011—2020)[J]. Bulletin of Mineralogy, Petrology and Geochemistry, 2021, 40(3): 515-519.
[3] 翟明国, 吴福元, 胡瑞忠, 等. 战略性关键金属矿产资源: 现状与问题[J]. 中国科学基金, 2019, 33(2): 106−111.
Zhai M G, Wu F Y, Hu R Z, et al. Critical metal mineral resources: Current reasearch status and scientific issues[J]. Sciences Foundation in China, 2019, 33(2): 106−111.
[4] 曾江萍, 王家松, 朱悦, 等. 敞开酸溶-电感耦合等离子体质谱法测定铀矿石中15种稀土元素[J]. 岩矿测试, 2022, 41(5): 789−797.
Zeng J P, Wang J S, Zhu Y, et al. Determination of 15 rare earth elements in uranium ore by open acid dissolution-inductively coupled plasma-mass spectrometry[J]. Rock and Mineral Analysis, 2022, 41(5): 789−797.
[5] 龚仓, 丁洋, 陆海川, 等. 五酸溶样-电感耦合等离子体质谱法同时测定地质样品中的稀土等28种金属元素[J]. 岩矿测试, 2021, 40(3): 340−348.
Gong C, Ding Y, Lu H C, et al. Simultaneous determination of 28 elements including rare earth elements by ICP-MS with five-acid dissolution[J]. Rock and Mineral Analysis, 2021, 40(3): 340−348.
[6] 张元, 王文东, 卢兵, 等. 碱熔-阳离子交换树脂分离ICP-MS法测定厚覆盖区地球化学调查样品中硼锗溴钼锡碘钨[J]. 岩矿测试, 2022, 41(1): 99−108.
Zhang Y, Wang W D, Lu B, et al. Determination of boron, germanium, bromine, molybdenum, tin, iodine and tungsten in geochemical survey samples by ICP-MS with alkali fusion-cation exchange resin seperation[J]. Rock and Mineral Analysis, 2022, 41(1): 99−108.
[7] Zhu L Y, Liu Y S, Hu Z C, et al. Simultaneous determination of major and trace elements in fused volcanic rock powders using a hermetic vessel heater and LA-ICP-MS[J]. Geostandards and Geoanalytical Research, 2013, 37(2): 207−229. doi: 10.1111/j.1751-908X.2012.00181.x
[8] Hu Z C, Qi L. Sample digestion methods, Volume 15: Analytical geochemistry/Inorganic INSTR. Analysis[J]. Treatise on Geochemistry (Second Edition), 2014: 87−109.
[9] He Z W, Huang F, Yu H M, et al. A flux-free fusion technique for rapid determination of major and trace elements in silicate rocks by LA-ICP-MS[J]. Geostandards and Geoanalytical Research, 2015, 40(1): 5−21.
[10] Zhang C X, Hu Z C, Zhang W, et al. Green and fast laser fusion technique for bulk silicate rock analysis by laser ablation-inductively coupled plasma mass spectrometry[J]. Analytical Chemistry, 2016, 88(20): 10088−10094. doi: 10.1021/acs.analchem.6b02471
[11] 胡靓, 张德贤, 娄威, 等. 含膏盐建造铁矿床中磁铁矿LA-ICP-MS微量元素测定与地球化学特征研究[J]. 岩矿测试, 2022, 41(4): 564−574.
Hu L, Zhang D X, Lou W, et al. In situ LA-ICP-MS determination of trace elements in magnetite from a gypsum-salt bearing iron deposit and geochemical characteristics[J]. Rock and Mineral Analysis, 2022, 41(4): 564−574.
[12] Lv N, Chen K Y, Bao Z A, et al. Non-matrix-matched 9μm U-Pb dating of zircon using excimer laser ablation ICP-MS[J]. Atomic Spectroscopy, 2021, 42(2): 51−61.
[13] Xiao Y T, Yang J, Deng J, et al. Influence of spot size on LA-ICP-MS ablation behavior for synthetic calcium tungstate and silicate glass reference material NIST SRM610[J]. Atomic Spectroscopy, 2021, 42(1): 36−42. doi: 10.46770/AS.2021.01.006
[14] Zhang W, Hu Z C, Feng L P, et al. Accurate determination of Zr isotopic ratio in zircons by femtosecond laser ablation MC-ICP-MS with “wet” plasma technique[J]. Journal of Earth Science, 2022, 33(1): 67−75. doi: 10.1007/s12583-021-1535-7
[15] Li Z Q, Li F J, Chen Z A, et al. Provenance of late Mesozoic Strata and tectonic implications for the Southwestern Ordos Basin, North China: Evidence from detrital zircon U-Pb geochronology and Hf isotopes[J]. Journal of Earth Science, 2022, 33(2): 373−394. doi: 10.1007/s12583-021-1450-y
[16] Wu S, Karius V, Schmidt B C, et al. Comparison of ultrafine powder pellet and flux-free fusion glass for bulk analysis of granitoids by laser ablation-inductively coupled plasma-mass spectrometry[J]. Geostandards and Geoanalytical Research, 2018, 42(4): 575−591. doi: 10.1111/ggr.12230
[17] Garbeschönberg D, Müller S. Nano-particulate pressed powder tablets for LA-ICP-MS[J]. Journal of Analytical Atomic Spectrometry, 2014, 29(6): 990−1000. doi: 10.1039/C4JA00007B
[18] Gray A L. Solid sample introduction by laser ablation for inductively coupled plasma source mass spectrometry[J]. Analyst, 1985, 110(5): 551−556. doi: 10.1039/an9851000551
[19] Mochizuki T, Sakashita A, Iwata H, et al. Laser ablation for direct elemental analysis of solid samples by inductively coupled plasma mass spectrometry[J]. Bulletin of the Japan Institute of Metals, 1988, 33(4): 403−409.
[20] Jarvis K E, Williams J G. Laser-ablation inductively-coupled plasma-mass spectrometry (LA-ICP-MS)—A rapid technique for the direct, quantitative-determination of major, trace and rare-earth elements in geological samples[J]. Chemical Geology, 1993, 106(3-4): 251−262. doi: 10.1016/0009-2541(93)90030-M
[21] Perkins W T, Fuge R, Pearce N J G. Quantitative analysis of trace elements in carbonates using laser ablation inductively coupled plasma mass spectrometry[J]. Journal of Analytical Atomic Spectrometry, 1991, 6(6): 445−449. doi: 10.1039/ja9910600445
[22] Perkins W T, Pearce N J G, Jeffries T E. Laser ablation inductively coupled plasma mass spectrometry: A new technique for the determination of trace and ultra-trace elements in silicates[J]. Geochimica et Cosmochimica Acta, 1993, 57(2): 475−482. doi: 10.1016/0016-7037(93)90447-5
[23] Denoyer E R. Semiquantitative analysis of environmental materials by laser sampling inductively coupled plasma mass spectrometry[J]. Journal of Analytical Atomic Spectrometry, 1992, 7(8): 1187−1193. doi: 10.1039/ja9920701187
[24] Morrison C A, Lambert D D, Morrison R J S, et al. Laser ablation-inductively coupled plasma-mass spectrometry: An investigation of elemental responses and matrix effects in the analysis of geostandard materials[J]. Chemical Geology, 1995, 119(1-4): 13−29. doi: 10.1016/0009-2541(94)00064-F
[25] Holá M, Mikuška P, Hanzlíková R, et al. Tungsten carbide precursors as an example for influence of a binder on the particle formation in the nanosecond laser ablation of powdered materials[J]. Talanta, 2010, 80(5): 1862−1867. doi: 10.1016/j.talanta.2009.10.035
[26] O’Connor C, Landon M R, Sharp B L. Absorption coefficient modified pressed powders for calibration of laser ablation inductively coupled plasma mass spectrometry[J]. Journal of Analytical Atomic Spectrometry, 2007, 22(3): 273−282. doi: 10.1039/B612512C
[27] Arroyo L, Trejos T, Gardinali P R, et al. Optimization and validation of a laser ablation inductively coupled plasma mass spectrometry method for the routine analysis of soils and sediments[J]. Spectrochimica Acta Part B-Atomic Spectroscopy, 2009, 64(1): 16−25. doi: 10.1016/j.sab.2008.10.027
[28] Mukherjee P K, Khanna P P, Saini N K. Rapid determination of trace and ultra trace level elements in diverse silicate rocks in pressed powder pellet targets by LA-ICP-MS using a matrix-independent protocol[J]. Geostandards and Geoanalytical Research, 2014, 38(3): 363−379. doi: 10.1111/j.1751-908X.2013.012015.x
[29] Godfred O D, Ashantha G, Charlotte A, et al. Determination of refractive and volatile elements in sediment using laser ablation inductively coupled plasma mass spectrometry[J]. Analytica Chimica Acta, 2015, 898: 19−27. doi: 10.1016/j.aca.2015.09.033
[30] Zhang W, Hu Z C. Recent advances in sample preparation methods for elemental and isotopic analysis of geological samples[J]. Spectrochimica Acta Part B-Atomic Spectroscopy, 2019, 160: 105690−105706. doi: 10.1016/j.sab.2019.105690
[31] Hu Z C, Gao S, Liu Y S, et al. NH4F assisted high pressure digestion of geological samples for multi-element analysis by ICP-MS[J]. Journal of Analytical Atomic Spectrometry, 2010, 25(3): 408−413. doi: 10.1039/b921006g
[32] Hu Z C, Zhang W, Liu Y S, et al. Rapid bulk rock decomposition by ammonium fluoride (NH4F) in open vessels at an elevated digestion temperature[J]. Chemical Geology, 2013, 355: 144−152. doi: 10.1016/j.chemgeo.2013.06.024
[33] Jochum K P, Nohl U, Herwig K, et al. GeoReM: A new geochemical database for reference materials and isotopic standards[J]. Geostandards and Geoanalytical Research, 2005, 29(3): 333−338. doi: 10.1111/j.1751-908X.2005.tb00904.x
[34] Liu Y S, Hu Z C, Gao S, et al. In situ analysis of major and trace elements of anhydrous minerals by LA-ICP-MS without applying an internal standard[J]. Chemical Geology, 2008, 257(1-2): 34−43. doi: 10.1016/j.chemgeo.2008.08.004
-
图(6)
表(1)
计量
- 文章访问数: 769
- PDF下载数: 74
- 施引文献: 0