Solid-state electrochemical characterization of emissions and authorities producing Roman brass coins

The voltammetry of immobilized particles (VIMP) is applied to describe the solid state electrochemistry of brass. This methodology, which involves sampling at the nanogram level, is applied to discriminate mints/authorities producing different Roman monetary emissions covering since the Republic (88 BCE) to Domitianus (55–96 CE) Upon attachment to graphite electrodes in contact with aqueous acetate buffer at pH 4.75, well defined voltammetric responses were obtained centered on Cu- and Zn-localized signals whose intensity can be correlated to EMP data, being sensitive to the contents of Zn (15–30 wt.%) and Sn (0.01–1.1 wt.%). Voltammetric data, combined with ATR-FTIR and FIB-FESEM/EDS, yield information on the structure of the metal patina and permit to characterize different monetary emissions being able, in the case of Augustus’ sestertii, to discriminate between the productions from different monetary authorities.