测试对象：岩石、土壤、沉积物、海水、地下水

测试周期：45-90个工作日，可提供样品测试加急服务。

送样要求：

完成标准：前处理在超净室100级超净台内进行，保证监测空白及样品无污染，标样和重复样在允许误差范围内。
标样数据：

方法描述：
10.1全岩Sr同位素比值分析
全岩Sr同位素前处理和测试由武汉上谱分析科技有限责任公司完成。
前处理流程：
前处理在配备100级操作台的千级超净室完成。样品消解：（1）将200目样品置于105℃烘箱中烘干12小时；（2）准确称取粉末样品50-200mg置于Teflon溶样弹中；（3）依次缓慢加入1-3ml高纯HNO₃和1-3ml高纯HF；（4）将Teflon溶样弹放入钢套，拧紧后置于190℃烘箱中加热24小时以上；（5）待溶样弹冷却，开盖后置于140℃电热板上蒸干，然后加入1ml HNO₃ 并再次蒸干；（6）用1.5ml的HCl（2.5M）溶解蒸干样品，待上柱分离。化学分离：用离心机将样品离心后，取上清液上柱。柱子填充AG50W树脂。用2.5M HCl淋洗去除基体元素。最终用2.5M HCl将Sr从柱上洗脱并收集。收集的Sr溶液蒸干后等待上机测试。树脂残留物质通过4.0M HCl淋洗可获得REE溶液。接收的REE溶液蒸干后以0.18M HCl提取，用于Nd同位素分离。
一次分离获得的溶液首先转换为3M HNO₃介质，然后样品上柱。柱子填充Sr树脂。采用3M HNO₃淋洗去除干扰元素。最终用MQ H₂O将Sr从柱上洗脱并收集。收集的Sr溶液蒸干后等待上机测试。
仪器测试流程：
Sr同位素分析采用德国Thermo Fisher Scientific 公司的MC-ICP-MS（Neptune Plus）。仪器配备9个法拉第杯接收器。⁸³Kr⁺、¹⁶⁷Er⁺⁺、⁸⁴Sr⁺、⁸⁵Rb⁺、⁸⁶Sr⁺、¹⁷³Yb⁺⁺、⁸⁷Sr⁺、⁸⁸Sr⁺同时被L4、L3、L2、L1、C、H1、H2、H3等8个接收器接收。其中⁸³Kr⁺、⁸⁵Rb⁺、¹⁶⁷Er⁺⁺、¹⁷³Yb⁺⁺被用于监控并校正Kr、Rb、Er和Yb对Sr同位素的同质异位素干扰。MC-ICP-MS采用了H+S锥组合和干泵以提高仪器灵敏度。根据样品中的Sr含量，50 µl/min-100 µl/min两种微量雾化器被选择使用。Alfa公司的Sr单元素溶液被用于优化仪器操作参数。Sr国际标准溶液（NIST 987，200 µg/L）的⁸⁸Sr信号一般高于7V。数据采集由8个blocks组成，每个block含10个cycles，每个cycle为4.194秒。
Sr同位素的仪器质量分馏采用内标指数法则校正（Russell et al. 1978）：

公式中i和j指示同位素质量数，R_m和R_T分别代表样品的测试比值和参考值（推荐值），f指仪器质量分馏因子。⁸⁸Sr/⁸⁶Sr被用于计算Sr的质量分馏因子（8.375209，Lin et al. 2016）。由于前期有效的样品分离富集处理，干扰元素Ca、Rb、Er、Yb被分离干净。残余的⁸³Kr⁺、⁸⁵Rb⁺、¹⁶⁷Er⁺⁺、¹⁷³Yb⁺⁺等干扰校正采用Lin et al.（2016）校正方法实验流程采用两个Sr同位素标样（NIST 987和AlfaSr）之间插入7个样品进行分析。全部分析数据采用专业同位素数据处理软件“Iso-Compass”进行数据处理（Zhang et al., 2020）。NIST 987的⁸⁷Sr/⁸⁶Sr分析测试值为0.710242±14（2SD, n=345），与推荐值0.710248±12（Zhang and Hu, 2020）在误差范围内一致，表明本仪器的稳定性和校正策略的可靠性满足高精度的Sr同位素分析。
BCR-2（玄武岩）和RGM-2（流纹岩）（USGS）被选择作为流程监控标样。两个样品分别代表了基性岩和酸性岩，具有显著的物理化学差异。RGM-2的具有较高的Rb含量（149 µg/g）和适中的Sr含量（108 µg/g）,可以有效监控Rb的分离过程和测试结果。BCR-2的⁸⁷Sr/⁸⁶Sr分析测试值为0.705012±22 （2SD, n=63），与推荐值0.705012±20（Zhang and Hu, 2020）在误差范围内一致。RGM-2的⁸⁷Sr/⁸⁶Sr分析测试值为0.704173±20 （2SD, n=20），与推荐值0.704184±10（Li et al. 2012）在误差范围内一致。数据表明，本实验流程可以对样品进行有效分离，分析准确度和精密度满足高精度的Sr同位素分析。
本测试方法适用Sr含量>20ppm的岩石样品，保证实际样品测试内精度（2SE）=0.000010-0.000020（0.01‰~0.03‰，2RSE），准确度优于0.000020（~0.03‰）。Sr含量低于20ppm的岩石样品，内精度和准确度会受到影响，影响程度受样品Sr含量控制。低Sr样品分析请事先咨询技术人员，确保样品分析质量。
10.2. Scheme for Sr isotope ratio analyses using MC-ICP-MS
All chemical preparations were performed on class 100 work benches within a class 1000 over-pressured clean laboratory. Sample digestion: (1) Sample powder (200 mesh) were placed in an oven at 105 ℃ for drying of 12 hours; (2) 50-200 mg sample powder was accurately weighed and placed in an Teflon bomb; (3) 1-3 ml HNO₃ ａnd 1-3 ml HF were added into the Teflon bomb; (4) Teflon bomb was putted in a stainless steel pressure jacket and heated to 190 ℃ in an oven for >24 hours; (5) After cooling, the Teflon bomb was opened and placed on a hotplate at 140 ℃ and evaporated to incipient dryness, and then 1 ml HNO₃ was added and evaporated to dryness again; (6) The sample was dissolved in 1.5 mL of 2.5 M HCl. Column chemistry: After centrifugation, the supernatant solution was loaded into an ion-exchange column packed with AG50W resin. After complete draining of the sample solution, columns were rinsed with 2.5 M HCl to remove undesirable matrix elements. Finally, the Sr fraction was eluted using 2.5 M HCl and gently evaporated to dryness prior to mass-spectrometric measurement. The residue was rinsed with 10 mL of 4.0 M HCl and then the REE fraction was eluted using 10 ml of 4.0 M HCl. The REE solution was used to separate the Nd fraction by the Nd-column method.
The Sr fraction was separated again by the Sr-specific resin. The solution was first converted to the HNO₃ media (3 M HNO₃). Then the solution was loaded into the Sr-specific resin and pre-conditioned with 6 M HCl and 3 M HNO₃. After complete draining of the sample solution, columns were rinsed with 3 M HNO₃ to remove undesirable matrix elements. Finally, Sr was eluted using MQ H₂O and gently evaporated to dryness prior to mass-spectrometric measurement.
Sr isotope analyses were performed on a Neptune Plus MC-ICP-MS (Thermo Fisher Scientific, Dreieich, Germany) at the Wuhan Sample Solution Analytical Technology Co., Ltd, Hubei, China. The Neptune Plus, a double focusing MC-ICP- MS, was equipped with seven fixed electron multiplier ICs, and nine Faraday cups fitted with 10¹¹ Ω resistors. The faraday collector configuration of the mass system was composed of an array from L4 to H3 to monitor ⁸³Kr⁺、¹⁶⁷Er⁺⁺、⁸⁴Sr⁺、⁸⁵Rb⁺、⁸⁶Sr⁺、¹⁷³Yb⁺⁺、⁸⁷Sr⁺、⁸⁸Sr⁺. The large dry interface pump (120 m³ hr^-1 pumping speed) and newly designed H skimmer cone and  the standard sample cone were used to increase the instrumental sensitivity. Sr single element solution from Alfa (Alfa Aesar, Karlsruhe, Germany) was used to optimize instrument operating parameters. An aliquot of the international standard solution of 200 μg L⁻¹ NIST SRM 987 was used regularly for uating the reproducibility and accuracy of the instrument. Typically, the signal intensities of ⁸⁸Sr in NIST 987 were > ~7.0 V. The Sr isotopic data were acquired in the static mode at low resolution. The routine data acquisition consisted of ten blocks of 10 cycles (4.194 s integration time per cycle). The total time of one measurement lasted about 7 minutes.
The exponential law, which initially was developed for TIMS measurement (Russell et al. 1978) ａnd remains the most widely accepted and utilized with MC-ICP-MS, was used to assess the instrumental mass discrimination in this study. Mass discrimination correction was carried out via internal normalization to a ⁸⁸Sr/⁸⁶Sr ratio of 8.375209 (Lin et al. 2016). The interference elements Ca, Rb, Er, Yb have been completely separated by the exchange resin process. The remaining interferences of ⁸³Kr⁺、⁸⁵Rb⁺、¹⁶⁷Er⁺⁺、¹⁷³Yb⁺⁺ were corrected based on the mothed described by Lin et al. (2016). One international NIST 987 standard was measured every seven samples analyzed. All data reduction for the MC-ICP-MS analysis of Sr isotope ratios was conducted using “Iso-Compass” software (Zhang et al. 2020). Analyses of the NIST 987 standard solution yielded ⁸⁷Sr/⁸⁶Sr ratio of 0.710242±14（2SD, n=345）, which is identical within error to their published values 0.710248±12（Zhang and Hu, 2020）). In addition, the USGS reference materials BCR-2 (basalt) and RGM-2 (rhyolite) yielded results of 0.705012±22 （2SD, n=63） and 0.704173±20 （2SD, n=20） for ⁸⁷Sr/⁸⁶Sr, respectively, which is identical within error to their published values (Zhang and Hu, 2020； Li et al. 2012).
References
Li, C. F., Li, X. H., Li, Q. L., Guo, J. H., Yang, Y. H. (2012). Rapid and precise determination of sr and nd isotopic ratios in geological samples from the same filament loading by thermal ionization mass spectrometry employing a single-step separation scheme. Analytica Chimica Acta, 727 (10), 54–60. 
Lin J., Liu Y.S., Yang Y.H., Hu Z.C. (2016). Calibration and correction of LA-ICP-MS and LA-MC-ICP-MS analyses for element contents and isotopic ratios. Solid Earth Sciences, 1, 5–27.
Russell, W.A., Papanastassiou, D.A., Tombrello, T.A., (1978). Ca isotope fractionation on the earth and other solar system materials. Geochim. Cosmochim. Acta, 42 (8), 1075–1090.
Zhang W., Hu Z.C. (2020). Estimation of isotopic reference values for pure materials and geological reference materials. At. Spectrosc. 2020, 41 (3), 93–102.
Zhang W., Hu Z.C., Liu Y.S. (2020). Iso-Compass: new freeware software for isotopic data reduction of LA-MC-ICP-MS. J. Anal. At. Spectrom., 2020, 35, 1087–1096.