Accurate precious metal analysis is used to determine the precious metal content in various materials. The concentration of precious metals can vary from parts per million (ppm) or lower in an autocatalyst to almost 100% in jewellery alloys. There are over 400 procedures published for the analysis of precious metals. In the latest issue of Platinum Metals Review, Dippal Manchanda from The Birmingham Assay Office, UK, considers the benefits of using inductively coupled plasma-optical emission spectrometry (ICP-OES) and compares this technique with classical methods such as gravimetry.

This process determines the precious metal content in different materials (the analysis of platinum group metals (pgms) in powder and ore samples). Accurate determination is also crucial for fineness determination for the hallmarking of precious metals for jewellery. The precision and accuracy of the ICP technique makes it very suitable for this purpose. From the ICP-OES measurement, the amount of pgm can be calculated, giving the fineness of the original article, which is then punched or lasered onto the jewellery as part of the hallmark.

Commercial laboratories now routinely use ICP-OES to analyse pgm-containing powder and ore samples, after fire assay with nickel sulfide as the collector.

Source:

The Role of Inductively Coupled Plasma-Optical Emission Spectrometry in Determining the Fineness of Precious Metals 

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