Electrochemical analysis of the first Polish coins using voltammetry of immobilized particles

• A series of 20 of the first Polish coins was studied.
• The voltammetry of microparticles methodology was used.
• Two metal sources were probably used.
• The studied coins were probably produced in three mints.

A series of 20 denarii from Boleslaus the Brave (992–1025) and Mieszko II Lambert (1025–1034), corresponding to the beginning of the Polish state were studied using the voltammetry of immobilized particles (VIMP) methodology. VIMP experiments, applied to nanosamples of the corrosion layers of the coins in contact with aqueous acetate buffer, provided well-defined responses mainly corresponding to the corrosion products of copper and lead. Such voltammetric responses, combined with X-ray fluorescence (XRF) spectroscopy experiments performed on the same set of coins, and complemented by focusing ion beam-field emission scanning electron microscope (FIB-FESEM) on silver coins from the 19th century, supported the hypothesis that two different metal sources were used in the former historical period and suggested that the coins were produced in three different mints.