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The Mars Organic Molecule Analyzer instrument (MOMA) in the Exomars Rosalind Franklin rover can analyse Mars samples with different technics: Laser Desorption-Mass Spectrometry, Pyrolysis-Gas Chromatography-Mass Spectrometry (Pyr-GC-MS), and derivatisation followed by GC-MS. For the last one, three different derivatisation reagents are available and can be used depending on the molecular families to be functionalised: TMAH, DMF-DMA and MTBSTFA. They are sealed in metallic capsules opening at a specific temperature using relevant eutetics. Hence, the sample can be heated in the oven before reacting with the reagent. This can enable to dry the sample, removing most of the free water present in the sample that could consume a part of the reagent, and to proceed to a thermal extraction of the organic molecules, enhancing their recovery yield. However, compared with classical routine laboratory procedures, this in-situ wet chemistry sample preparation implies very specific conditions due to this one pot one step system and space instrumental constraints in term of weight, operational temperature and available energy. We focused our work on GC-MS with sample derivatisation by MTBSTFA. This reagent is kept in tight capsules that open only at 221°C whereas routine similar laboratory derivatisation reactions are usually done at about 75°C in the presence of DMF. The targeted molecules are the amino acids (AAs), linear carboxylic acids (CAs) and aromatic CAs that could be preserved on Mars (benzoic, phtalic, trimesic and mellitic acids). In order to optimise the time of preparation of the samples, a series of experiments was carried out with laboratory instruments with standards and Orbagnoux soil (Kimmerdgian, late Jurassic). First, the influence of the temperature of derivatisation and the absence of DMF on the derivatisation of AAs and CAs was studied. It showed that the presence of DMF provides a better derivatisation for AAs with fully derivatised products while many partially derivatised by-products appear otherwise. Consequently, there is a decrease of the signal for most of the amino acids. Additionally, several processes may occur upon heating at 221°C to reach the eutectic temperature (chemical decomposition, condensation), leading to the apparition of other by-products. Some of them can be used as new markers while some could create misinterpretation of the data results on Mars like the a-aminobutyric acid. Therefore, building a database, including the mass spectra and retention times of all these molecules seems necessary. The derivatisation of AA is optimum after a 4-minute reaction. The results obtained for carboxylic acids are, however, more encouraging. Indeed, without DMF the difference in yield is slight for linear CAs, while its seems to favour the aromatic CAs derivatisation. Besides, high temperature decreases the reaction yield for linear CAs with 16 carbon atoms and higher, but provides a better derivatisation yield with aromatic CAs (Figure 1). Figure 1: Aromatic carboxylic acids analysis comparaison between standards laboratory and MOMA condition derivatization. Secondly, the extraction of carboxylic acid present in a soil matrix by thermal desorption at 200°C was studied on crushed fragments of natural terrestrial rocks from Orbagnoux. The analysis of the extracted molecules was carried out with a microreactor pyrolyse, enabling a one pot one step protocol as used for MOMA. First results indicated the detection after extraction of hexanoic acid (C₅H₁₁COOH), glycolic acid (C₂H₄O₃) and oxalic acid (C2H2O4). Extraction of CAs is incomplete if the thermal desorption step last less than 5 min, while a time greater than 7.5 min appears to degrade them. Optimization of CAs extraction is needed for the different soil matrices available for this study (other natural terrestrial rocks and extraterrestrial material as Murchison meteorite). The optimum time for CAs thermal desorption is also checked against optimum time for AAs. The total time of preparation is calculated as a function of the oven temperature ramp and shall be taken into account when programming a run. We wish to have the longest run to detect as much products as possible, better extraction and sensibility but due to the rover operation constrains we have a limited time and/or energy budget. However, compromises can be found to have an optimized trade-off between operational constrains and science return. To validate the final protocol, Mars analog samples need to be extracted and analysed efficiently with the optimised parameters. The construction of a MOMA-like oven in our laboratory, coupled to a commercial GC-MS should enable to test our procedures with an analytical system close to the real MOMA instrument.

The proteomic analysis of hairs, yarns or textiles has emerged as a powerful method to determine species of origin, mainly used in archaeozoological research and fraud control. Differentiation between the South American camelid (SAC) species (the wild guanaco and vicuna and their respective domesticates the llama and alpaca) is particularly challenging due to poor database information and significant hybridization between species. In this study, we analysed 41 modern and 4 archaeological samples from the four SACs species. Despite strong similarities with Old World Camelidae, we identified 7 peptides specific to SACs assigned to keratin K86 and the keratin-associated proteins KAP13-1 and KAP11-1. Untargeted multivariate analysis of the LC-MS data permitted to distinguish SAC species and propose discriminant features. MS/MS-based molecular networking combined with database-assisted de novo sequencing permitted to identify 5 new taxonomic peptides assigned to K33a, K81 and/or K83 keratins and KAP19-1. These peptides differentiate the two wild species, guanaco and vicuna. These results show the value of combining database search and untargeted metabolomic approaches for paleoproteomics, and reveal for the first time the potential of molecular networks to highlight deamidation related to diagenesis and cluster highly similar peptides related to interchain homologies or intra- or inter-specific polymorphism. SIGNIFICANCE: This study used an innovative approach combining multivariate analysis of LC-MS data together with molecular networking and database-assisted de novo sequencing to identify taxonomic peptides in palaeoproteomics. It constitutes the first attempt to differentiate between hair fibres from the four South American camelids (SACs) based on proteomic analysis of modern and archaeological samples. It provides different proteomic signatures for each of the four SAC species and proposes new SAC taxonomic peptides of interest in archaeozoology and fraud control. SACs have been extensively exploited since human colonization of South America but have not been studied to the extent of their economic, cultural and heritage importance. Applied to the analysis of ancient Andean textiles, our results should permit a better understanding of cultural and pastoral practices in South America. The wild SACs are endangered by poaching and black-market sale of their fibre. For the first time, our results provide discriminant features for the determination of species of origin of contraband fibre.

International audience; The sandarac resin (Tetraclinis articulata) has been long used for its properties, mostly as a varnish component. Called juniper resin until the nineteenth century, the real botanical origin of sandarac is still unclear. The first approach to this issue is the review of the evolution of the etymology, terminology, and botanical description of sandarac through time. It seems that sandarac was mainly coming from T. articulata but the use of some juniper resins before the twentieth century is not to be excluded. The second approach is a chemical one; we used gas chromatography coupled to mass spectrometry to characterise the resin. As sandarac was the main component of the famous Italian varnish Vernice liquida, its characterisation is important for old paintings studies. However, although we could hope to differentiate sandarac, Juniperus communis and Juniperus oxycedrus resins by looking at their chemical composition, it appears that these resins are very similar. Besides, we notice a lack of old varnishes containing sandarac which complicates our work.

International audience; 18 Textile technology strongly advanced with sedentism and pastoralism. During prehistory, many 19 populations settled in central Eurasia, a place of extensive exchange and cultural contact. In the 20 Taklamakan desert, the dry climate enabled good preservation of ancient textiles. The study presented 21 here aimed to identify animal fibres from Bronze Age and Iron Age sites in the Keriya valley 22 (Xinjiang, China) using proteomics. A large corpus of 109 keratin extracts obtained from raw fibres or 23 textiles was analysed, enabling us to establish a corrected and improved list of peptide markers for the 24 identification of species, not only among the family Bovidae, but also for camels and humans. In total, 25 we were able to identify 97% of the sampled objects to the taxonomic level of tribe and 85% of 26 caprines to the level of genus. The assemblage was dominated by hair of sheep (57.8%) followed by 27 goat (16.5%), cattle (8.3%), camel (0.9%), human (0.9%) and non-differentiated Caprinae (sheep or 28 goat) (12.8%). The study showed a continuity between the two sites in this respect. It revealed a 29 choice of raw material linked to the function of the textile, with most woven textiles being made from 30 sheep's wool and most pelt being obtained from goat. Comparison with the bone assemblage of one of 31 the sites provided insight into the herd management strategies. The results confirm the heuristic 32 potential of the proteomic approach for the determination of archaeological fibres and for textiles 33 studies in general. Data are available via ProteomeXchange with identifier PXD012189. 34