Gold is traded in virtually every country around the world. Consequently, tracing gold provenance is a difficult but necessary task to ensure a responsible supply chain from deposit to consumer. Measuring the silver content is often the first step in characterizing gold to retrace its origin. In this study, laser-induced breakdown spectroscopy (LIBS) using a handheld instrument was evaluated as a fast and easy method to analyse the silver content in natural gold. Six commercial gold alloys and natural gold from French Guiana were used. Our results demonstrate that handheld LIBS is relevant to gold traceability and is simple to use in the field. The micron-scale focused laser beam allows in situ analyses of small gold grains with acceptable reproducibility. Univariate and multivariate regression modelling was performed to assess the best calibration model for quantification of the Ag content. The quadratic univariate model was selected for its good predictive ability, with a coefficient of determination R² of 0.99 and a mean average error of 0.36 wt% Ag for prediction. The LIBS analyses of natural gold were compared to the EPMA data using a statistical test that allow distinct gold populations to be discriminated (or matched) and the results indicate it would be suitable for identifying unknown samples. We were able to successfully trace the origin of our “unknown” samples, a promising first step in the goal of delivering a low-cost field-based tool for responsible supply chain management.

中文翻译：

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手持式激光诱导击穿光谱法（LIBS）作为快速，简便的金追踪方法

黄金几乎在世界每个国家都交易。因此，要追踪金的出处是一项困难但必要的任务，以确保从存款到消费者的负责任的供应链。测量银含量通常是表征金特征以追溯其来源的第一步。在这项研究中，使用手持仪器的激光诱导击穿光谱法（LIBS）被评估为分析天然金中银含量的一种快速简便的方法。使用了六种来自法属圭亚那的商业金合金和天然金。我们的结果表明，手持式LIBS与金的可追溯性有关，并且在现场易于使用。微米级聚焦激光束允许原位可接受的重现性对小金粒进行分析。进行了单变量和多变量回归建模，以评估最佳校准模型以量化Ag含量。选择具有良好预测能力的二次单变量模型，其确定系数为R ²0.99，Ag的平均平均误差为0.36 wt％。使用统计测试将天然金的LIBS分析与EPMA数据进行比较，该统计测试可区分（或匹配）不同的金族，结果表明该方法适合鉴定未知样品。我们能够成功追踪“未知”样本的来源，这是朝着提供低成本，基于现场的工具进行负责任的供应链管理的目标迈出的有希望的第一步。