Silver coin chemical composition two-parameter control system: measuring instruments selection for mass fraction of components

The article considers general requirements for quality control of precious metal products. It presents an algorithm for developing a quality control system for silver coins and features of its application in monitoring the chemical composition of coins with a silver content of 79.7% to 92.8% (the balance is copper). An algorithm has been developed for making decisions based on the two-parameter control results, including mathematical models for calculating the indicators of control reliability (the probability of types I and II errors). The calculation of the errors in measuring mass fractions of silver and copper (standard deviation) was performed with the required reliability (the probability of type I errors is 0.10). The article describes the dependence of the probability of type I errors on the error (standard deviation) of mass fraction of alloy components in silver coins measurement result, which can be used to justify the requirements for the indicators of measurement accuracy. Based on the criteria “Analyzed elements”, “Measurement range”, “Error”, X-ray fl uorescence spectrometers were proposed for use in the control system. The described algorithm for developing a controlsystem and its implementation in monitoring the chemical composition of silver coins will be useful to employees involved in precious metals and jewelry in specialized institutes and organizations in the manufacturing industry, banks, jewelry stores, pawnshops.