Search

In this paper we report the results of a deep investigation of gold title in jewellery alloys by means of potentiometric titration. After reviewing the suitable reactions for such purpose we focused on the most profitable one, which involves the use of hexadecylpyridinium chloride (CPC). This cation gives rise to selective and quantitative precipitation of AuCl . We completely revised a method previously proposed by W.S. Selig in the 80's, by improving the sampling preparation and by optimizing the titration steps. Then, the new proposed method was tested on a large number of different alloys, commonly used for goldsmithery purposes. The obtained gold titles were compared with the data achieved by fire assay, giving rise to a very good agreement. At the light of these results, the present method can be rightfully considered a cheaper and 'greener' alternative to the traditional one. [ABSTRACT FROM AUTHOR]

The results from a study of the real scope of energydispersive X-ray fluorescence analysis in an Assay Office, in which precious metal samples must be analysed prior to their hallmarking according to Spanish regulations, are presented. The advantages and limitations of this technique for the analysis of gold and silver jewellery samples, which is one of the most significant industrial activities in the local area (Cordoba, Spain), are reported. The results of gold and silver support the use of this technique in Assay Offices, not only for screening purposes, but also as an alternative to cupellation and potentiometric titration for a number of samples. The application of the energy-dispersive X-ray fluorencence spectrometer for the detection of plating layers like rhodium and nickel is also discussed. [ABSTRACT FROM AUTHOR]