The determination of the conformity of the samples is currently based on statistical (for level 1) and graphical (for levels 2 and 3) evaluation. The choosen statistical interpretation is an extremely sensitive analytical tool, which can reveal very small variations in chemical composition. These refer, for example, to different suppliers in the context of gold collectors, changes in the pre-refining process, variations related to the gold deposit, but also to mixtures of several sources not necessarily declared, or even false declarations of origin. With our method, a change, even minimal and of any kind, can be detected immediately. As a consequence, too many doré bars are declared as non-compliant at the end of this first selection stage.
We want to better understand the different possible influences on the isotopic and chemical composition of a doré bar by studying the entire supply of three suppliers (one collector and two suppliers) over a two-year period. The samples required for this study will be supplied by Metalor. The samples will be analysed at the University of Geneva (isotopes by MC-ICP-MS) and at the University of Lausanne (chemical composition by LA-ICP-MS).
Through this sub-project, we hope to improve the selection procedure of step 1 and the understanding of the non-compliance of doré bars.
Supported by : Metalor, by providing the samples necessary for this study.
Research partner: UNIL, UNIGE
Duration of this sub-project: 18 months, part time
Financial resources required: CHF 200’000.- including analytical costs
Already supported funding: CHF 0.-