Modern coin debasement discovered by combined portable X-ray fluorescence and atomic absorption spectroscopy in Peruvian cent coins (1950-1965)

摘要

A series of one- and two-cent coins minted in Peru from 1950 to 1965 has been analyzed by portable X-ray fluorescence (pXRF), and the results have been calibrated by atomic absorption spectroscopy (AAS). These coins were expected to be composed of zinc and copper (95:5 wt/wt), but results show that the copper content changes from year to year and usually tends to be smaller than the legally acceptable limits (below 3 wt%). The nondestructive X-ray fluorescence analysis of the Cu/Zn ratio was calibrated with AAS. The pXRF results of 313 coins show a debasement over time with two minimums, one in 1954 (observed in both types of coins) and the second one in 1959 (present only in one-cent coins), in agreement with adverse economic events in this time frame. This is the first time that Peruvian coin debasement is studied with this particular nondestructive technique and correlated with a series of economic events in the country.