CEA, DAM, DIF, 91297, Arpajon, France.
Universite de Pau et des Pays de l'Adour, E2S UPPA, CNRS, IPREM, Avenue de l'Université, 64012, PAU Cedex, France.
Anal Sci. 2023 Jun;39(6):999-1014. doi: 10.1007/s44211-023-00309-5. Epub 2023 Mar 1.
Sample preparation is a crucial point for quantitative multi-elemental analses by LA-ICP-MS of powdered geological materials. Four different methods are compared in this study with respect to signal stability and intensity as follows: the preparation of glass beads (GlassB) by alkaline fusion method and three grinding and pelletizing methods relying on the use of an organic binder (VanBind, vanillic acid), an adhesive binder (MixGlue, methyl methacrylate) and a sol-gel process for glass formation (SolGel, chemical reaction of tetraethoxysilane), respectively. Sixty elements were analyzed by means of a ns-UV (213 nm) laser ablation system coupled to a single collector sector field ICP-MS with a low or medium mass resolution. Signal stability was found to strongly depend on the sample homogeneity provided by the preparation method. These methods were applied to three geological standard materials (CRM). The following criteria were used to evaluate and compare the methods: (1) proportion of the measurement cycles which are above a given signal intensity threshold (defined here as signal average ± 3 times the standard deviation), (2) signal stability of the analyzed nuclides (internal precision estimated by the relative standard deviations on raw count rates), (3) signal stability of the internal standards added to the samples, (4) external precision estimated by the relative standard deviation over five preparations for each geological CRM. For the majority of the analyzed elements, signals measured for samples prepared with the four methods are reproducible. Specific contamination in one or several elements (Cr, Fe, Co, Ni, Cu, Mo, W, Au and Bi) was observed depending on the sample preparation method. In addition, compared to grinding made with PTFE material, grinding performed with tungsten carbide material was found to produce better homogeneity, especially for the sol-gel and mixing with glue protocols, although some metallic contamination (W and Co) was observed. Thanks to the suppression of grain effects by alkaline melting, the glass bead method systematically provided signal stability and percentage of "over the threshold" close to those of the NIST glasses. This may be explained by the preparation of more homogeneous samples by alkaline melting. Finally, the described methods were found to be reproducible for the majority of the analyzed elements.
样品制备是粉末状地质材料通过激光烧蚀电感耦合等离子体质谱法进行定量多元素分析的关键环节。本研究比较了以下四种不同的方法：碱熔法制备玻璃珠（GlassB）和三种研磨压片方法，分别依赖于使用有机粘结剂（VanBind、香草酸）、粘结剂（MixGlue、甲基丙烯酸甲酯）和溶胶-凝胶法形成玻璃（SolGel、四乙氧基硅烷的化学反应）。使用纳秒紫外（213nm）激光烧蚀系统，结合具有低或中质量分辨率的单收集器扇形场 ICP-MS 分析了 60 种元素。研究发现，信号稳定性强烈依赖于制备方法提供的样品均匀性。这些方法应用于三种地质标准物质（CRM）。采用以下标准来评估和比较这些方法：（1）超过给定信号强度阈值（此处定义为信号平均值±3 倍标准偏差）的测量周期比例；（2）分析核素的信号稳定性（通过原始计数率的相对标准偏差估算内部精密度）；（3）添加到样品中的内标信号稳定性；（4）对于每种地质 CRM，通过五个制备物估计的外部精密度。对于大多数分析元素，用四种方法制备的样品测量的信号具有可重复性。取决于样品制备方法，观察到一个或几个元素（Cr、Fe、Co、Ni、Cu、Mo、W、Au 和 Bi）存在特定污染。此外，与使用聚四氟乙烯材料研磨相比，使用碳化钨材料研磨发现可产生更好的均匀性，特别是对于溶胶-凝胶和混合胶协议，尽管观察到一些金属污染（W 和 Co）。由于碱性熔融抑制了晶粒效应，玻璃珠法系统地提供了接近 NIST 玻璃的信号稳定性和“超过阈值”的百分比。这可能是由于碱性熔融制备了更均匀的样品。最后，对于大多数分析元素，所描述的方法被发现具有可重复性。
