Handheld laser-induced breakdown spectroscopy (LIBS) as a fast and easy method to trace gold

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 thi...

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Bibliographic Details
Published in:Journal of analytical atomic spectrometry 2020-02, Vol.35 (2), p.254-264
Main Authors: Pochon, Anthony, Desaulty, Anne-Marie, Bailly, Laurent
Format: Article
Language:English
Subjects:
Earth Sciences
Gold
Gold base alloys
Laser beams
Laser induced breakdown spectroscopy
Lasers
Regression analysis
Sciences of the Universe
Silver
Spectrum analysis
Statistical analysis
Statistical methods
Statistical tests
Supply chains
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Summary: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 R 2 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. This study demonstrates the ability of a handheld LIBS unit to quantify the Ag content in order to trace the provenance of natural gold.
ISSN:0267-9477
1364-5544
DOI:10.1039/c9ja00437h