New advanced extraction and analytical methods applied to discrimination of different lichen species used for orcein dyed yarns. Preliminary results

In this paper, the preliminary results of a study aimed to discriminate between the different species of lichens, from which orchil dyes originate, are presented. A multi-analytical approach has been used to analyze several species of lichens, in particular Roccella tinctoria DC, Lasallia pustulata L. and Ochrolechia tartarea L., in an attempt to identify distinguishing markers within different orchil mixtures. In the first part of the research, samples of yarns dyed with the different species, prepared in laboratory after the proper raw lichens treatment, have been subjected to SERS on fiber analyses. Hence an innovative ammonia protocol has been applied to all the specimens. Firstly, in order to evaluate the difference among the different species, HPTLC has been applied to the extracts of dyed yarns and the dye baths. All the spots present on the TLC plates have been analyzed through SERS (HPTLC-SERS), in order to obtain a SERS database of each single compound, fixed on the yarns. Then, HPTLC- MS and HPLC-MS experiments have been carried out, in order to deep into the identification of compounds corresponding to each spot.