Multianalytical approach to aged complex matrices

Since a decade our research group deals with the analysis of ancient cosmetics and drugs, starting from the Roman founds. At present some founds from pharmacies of Italy (Genua, Sansepolcro) and Spain (Majorca) amounting to the XVII century and Egyptian ointments of the II millennium b.C. from the Turin Museum are under study. The analysis protocol provides firstly non-destructive analyses and then the more expensive and destructive analyses, such as gas-chromatography-mass spectrometry (GC-MS) methods. These measurements involve other research groups of our project supported by a national Fund (PRIN: Colours and ointments in antiquity). We report the results of the vibrational spectroscopy techniques, such as Raman microscopy (laser 632 nm), FT-Raman spectroscopy (laser 1064 nm) and FT-IR/ATR with a golden gate accessory, were identified as the most suitable techniques for a first approach to the analysis of the ancient samples. Raman microscopy is the most suitable technique in order to identify minor inorganic components and contaminants at the micrometric scale inside these complex matrices. This technique can easily identify compounds like lead oxide, vermillion, rare minerals, (etc.) that could give interesting informations about the provenance of the raw materials and the original composition of the formulate. Concerning the organic materials, their possibility of identification, is very different from that of inorganic ones. Some compounds were rapidly degraded, some others persisted till to present day, often unchanged (e.g. wax). Historical samples give a chemical variability like the natural products, in addiction there are the ageing and the degradation process that make very difficult to recognize the raw material originally present. For understanding the possible changes undergone by materials in ageing, a specific database of spectra must be available.Some thirty raw materials were chosen among oils (e.g. olive, almond, and palm oil), gums (e.g. gum arabic, gum tragacanth), animal fats and waxes commonly employed in the ancient preparations. On the basis of the examination and critical interpretation of ancient literature sources (pharmacopoeias) fifteen samples based on pharmaceutical and cosmetic recipes were prepared as a reference samples. The raw materials and the reference formulations were artificially aged by using heating (in a oven at 60°C for 1 month), photo-oxidation (with ozone for 20 hours) and enzymatic degradation (by means of a pool of cellulase, lipase and laccase).Concerning the raw materials, only few showed fluorescence in Raman microscopy, but this decreases sharply with the artificial ageing process. This fact could be due to the loss of fluorophores. The artificial ageing produces different alterations according to the type of ageing. Among the first results we reported the analysis of Pompeii sample already identified as palm oil by GC-MS2. The comparison with our database showed correspondence with palm oil enzymatically degraded. This indicates that this database is interesting in recognising the organic materials associated to archaeological founds.