A round robin exercise in archaeometry: analysis of a blind sample reproducing a seventeenth century pharmaceutical ointment

Chemical analysis of ancient residues of pharmaceuticalor cosmetic preparations such as balms orointments is made problematic by the high complexity ofthese mixtures, composed of organic and inorganic materials.Consequently, a multi-analytical approach and specialcaution in the interpretation of the results are necessary. Inorder to contribute to the improvement of analyticalstrategies for the characterization of complex residues andto reconstruct ancient medical practices, a replica of a pharmaceutical formulation of the seventeenth century wasprepared in the laboratory according to a historicallydocumented recipe. In a round robin exercise, a portion ofthe preparation was analysed as a blind sample by 11laboratories using various analytical techniques. Theseincluded spectroscopic, chromatographic and mass spectrometricmethods. None of the laboratories was able tocompletely reconstruct the complex formulation, but eachof them gave partial positive results. The round robin exercise has demonstrated that the application of a multianalyticalapproach can permit a complete and reliablereconstruction of the composition. Finally, on the basis ofthe results, an analytical protocol for the study of residuesof ancient medical and pharmaceutical preparations hasbeen outlined.