The aim of this work is to examine whether it is possible to find chemical markers that allow a distinction to be made between the imported black glossed ‘Campanian A’ and the Sicilian imitation (end of fourth to first century bc) of these productions by carrying out quantitative chemical microanalysis of the slip using the SEM–EDS technique. The efficiency of the proposed analytical method has been tested on a set of ceramic samples corresponding to Sicilian black gloss imitations whose ceramic body has already been characterized petrographically by thin-section microscopy and chemically by XRF. The analytical data point to Na2O as a suitable chemical marker to distinguish between original ‘Campanian A’ imported from the Gulf of Naples area and Sicilian imitations of the same forms of Hellenistic pottery. In order to verify the above result, the enrichment factors (EFs) between the raw clays, the corresponding ceramic body and black gloss slip were calculated. Some differences in the patterns of EFs between original ‘Campanian A’ and Sicilian imitations were recognized and explained. Therefore, the obtained results can help to accomplish a first distinction between imported and local material on a firm analytical basis, working on a statistically significant number of individuals.