Liquid chromatography/tandem mass spectrometry analysis of chloramphenicol in propolis extracts available on the Italian market

This paper presents the results of an evaluation of chloramphenicol (CAP) levels in eight samples of propolis extracts considered to be the best-known brands of propolis specialities produced in Italy. The aim was to verify whether determination of CAP residues might be useful and appropriate in propolis derivatives in addition to other matrices previously studied. Hydroalcoholic and glycolic extract were simply diluted with ethyl acetate, and CAP was determined by monitoring the selective transition of two parent ions. These commercial products were analysed using liquid chromatography–tandem mass spectrometry method. Thiamphenicol as internal standard was used for quanitification. Detection of the analyte was achieved by negative ionization electrospray in the selected reaction monitoring (SRM) mode. For confirmation, two characteristic mass transitions were monitored, both for the analyte and the internal standard.