Van Ham-Meert Alicia, Bolea-Fernandez Eduardo, Belza Joke, Bevan Dan, Jochum Klaus Peter, Neuray Brigitte, Stoll Brigitte, Vanhaecke Frank, Van Wersch Line
Earth and Environmental Science, Centre for Archaeological Science, KU Leuven, Celestijnenlaan 200E, B-3001 Heverlee, Belgium.
Analytical, Environmental and Geochemistry, Vrije Universiteit Brussel, Triomflaan 2, B-1050 Elsene, Belgium.
ACS Omega. 2021 Jul 9;6(28):18110-18122. doi: 10.1021/acsomega.1c01939. eCollection 2021 Jul 20.
Different approaches for the determination of the Sr/Sr isotope ratio of high-Rb glass are compared in this work to assess the suitability of minimally invasive approaches for applications on medieval stained glass (from the ancient Abbey of Stavelot in Belgium). It was found that pneumatic nebulization multicollector inductively coupled plasma-mass spectrometry (PN-MC-ICP-MS) after acid digestion and chromatographic isolation of the target analyte out of the sample matrix can still be seen as the preferred method for the high-precision isotopic analysis of Sr in glass with high Rb and rare-earth element (REE) concentrations. Alternatively, the use of laser ablation (LA) for sample introduction is a powerful technique for the direct analysis of solid samples. However, both the high Rb/Sr ratios in the samples of interest and the presence of REEs at sufficiently high concentrations lead to a large bias in LA-MC-ICP-MS, which cannot be corrected for, even by operating the MC-ICP-MS instrument at higher mass resolution and/or using mathematical corrections. It was demonstrated that LA tandem-ICP-MS (LA-ICP-MS/MS) using CHF/He as the reaction gas to overcome spectral overlap in a mass-shift approach (chemical resolution) provides a viable alternative when (quasi) nondestructive analysis is required. This approach relies on the monitoring of Sr ( = 86, 87, and 88) ions as the corresponding SrF reaction product ions ( = 105, 106, and 107), thus avoiding the occurrence of spectral interference. Self-evidently, the isotope ratio precision attainable using sequential quadrupole-based ICP-MS instrumentation (0.3% RSD) was found to be significantly worse than that of high-precision MC-ICP-MS (0.03% RSD) with simultaneous detection, although it was still fit for the purpose of current applications. In addition to Sr isotopic analysis, the REE patterns and their potential influence on the Sr isotopic composition were evaluated by LA-ICP-MS.
本研究比较了测定高铷玻璃中锶/锶同位素比值的不同方法，以评估微创方法在中世纪彩色玻璃（来自比利时古老的斯塔韦洛修道院）应用中的适用性。研究发现，酸消解并从样品基质中色谱分离目标分析物后，采用气动雾化多接收电感耦合等离子体质谱法（PN-MC-ICP-MS）仍可视为对高铷和稀土元素（REE）浓度玻璃中锶进行高精度同位素分析的首选方法。另外，使用激光烧蚀（LA）进样是直接分析固体样品的有力技术。然而，感兴趣样品中的高铷/锶比值以及足够高浓度稀土元素的存在会导致LA-MC-ICP-MS出现较大偏差，即使通过在更高质量分辨率下操作MC-ICP-MS仪器和/或使用数学校正也无法校正。结果表明，当需要（准）无损分析时，使用CHF/He作为反应气以质量偏移方法（化学分辨率）克服光谱重叠的LA串联ICP-MS（LA-ICP-MS/MS）提供了一种可行的替代方法。该方法通过监测作为相应SrF反应产物离子（ = 105、106和107） 的锶（ = 86、87和88）离子，从而避免光谱干扰的发生。不言而喻，虽然基于串联四极杆的ICP-MS仪器可实现的同位素比值精密度（0.3% RSD）明显低于同时检测的高精度MC-ICP-MS（0.03% RSD），但仍适用于当前应用目的。除了锶同位素分析外，还通过LA-ICP-MS评估了稀土元素模式及其对锶同位素组成的潜在影响。
