Pyrolysis Coupled With Gas Chromatography And Mass Spectrometry Research Articles

Preserving the Ephemeral: A Micro-Invasive Study on a Set of Polyurethane Scenic Objects from the 1960s and 1970s.

Among the innovative materials used by 20th-century artists, polyurethane (PUR) has been shown to be highly unstable, and therefore artworks made of it are now in need of careful conservation strategies. This study presents a multi-analytical investigation of PUR foam scenic objects originally made between the 1960s and 1970s during the Italian Arte Viva movement. The main components in the foam and additives were characterized through micro attenuated total reflectance infrared spectroscopy (μ-ATR-FTIR) and pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC/MS). Painted samples were further investigated through μ-FTIR and Raman spectroscopy to define binders and pigments. The use of μ-ATR-FTIR in combination with evolved gas analysis-mass spectrometry (EGA-MS) allowed the variable conditions of the artworks to be assessed and attained some insights into the chemical processes responsible for aging. At the same time, morphological changes due to the degradation phenomena were recorded through optical (OM) and scanning electron microscopy (SEM). The detailed characterization of the PUR foam and painting materials was helpful in attaining some insights into harmful environmental parameters for the artworks, thus informing preventive conservation.

Application of GC/MS Pyrolysis for Assessment Residues of Textile Composites after Filtration of Washing and Rinsing Effluents

Research on the sources of microplastics (MP) in the environment and the parameters that lead to the loss of microfibers from synthetic textiles during washing have recently attracted public attention. Considering the involvement of a variety of structural and process parameters, it is important to choose methods for quantifying fibers as MP pollutants that migrated during the washing process. In the research to date, various sampling techniques and analytical protocols for the identification of polymers from washed synthetic textiles have been applied. In the present research, pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC/MS), was applied to verify the composition of the filter residue isolated from washing and rinsing effluents. A comparison with bases of polymeric materials has proven the presence of potential environmental pollutants in the form of microfibers released during the washing process. The investigation confirmed that fragments of cotton cellulose residues predominate in relation to polyester. Based on the list of identified compounds generated by Py-GC/MS results and their retention times the multivariate data analysis proved the influence in the bath composition.

Analytical pyrolysis (Py-GC-MS) for the assessment of olive mill pomace composting efficiency and the effects of compost thermal treatment

Composting is an interesting solution for recycling the large amount of residues typically generated in olive oil production areas, particularly olive mill pomace. Bulking agents must be added to wet olive mill pomace for composting. The diversity of the materials used (such as olive tree-pruning residues, animal manure, or straw) and the variable proportion, in which they are mixed, are responsible for the heterogeneity and variability of the quality of the produced compost. For this reason, a comprehensive characterization of compost organic matter is necessary to gain information about its stability and maturity useful as well as to predict its behavior as a soil amendment. In this work, fresh olive mill pomace and four composted olive mill pomace samples were characterized using analytical pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC-MS). Results showed a large variety of pyrolysis products, many of which had a specific biochemical origin. Pyrolysis-GC-MS revealed a decrease in fatty acids and aliphatic compounds content with composting, along with carbohydrates degradation and an increase in phenolic and N-compounds levels. Furthermore, the differences observed in organic matter characteristics had an impact on agronomic aspects (water repellency and phytotoxicity). Thus, the occurrence of fatty acids in incompletely composted materials (mainly palmitic and cis-vaccenic acids) was associated with increased phytotoxicity and higher water repellency. The presence of chicken manure in the mixtures was proved to favor the humification process and the production of stabilized compost (characterized by a lower Aliphatic-C/Aromatic-C ratio and higher N-heterocycles content). Furthermore, in this work, the effectiveness of applying thermal treatments to improve compost quality has been evaluated. Analysis of the Py-GC-MS results by means of principal component analysis (PCA) revealed thermal rearrangement, predominantly aromatization, and loss of functional groups of carbohydrates, lignin, and proteins, at temperatures above 225 ºC. Interestingly, the results suggest that materials with a non-effective or incomplete composting process can be transformed by thermal treatment into more stable products, exhibiting similar agronomic characteristics as those have that undergone a more efficient biotransformation.

Is this tar? Analytical pyrolysis to study the chemical composition of Alberto Burri’s paint materials

Alberto Burri, among the artists of the 20th century, was known for using some of the most complex and iconic “paint” techniques of this period, which entailed using a mixture of traditional and modern materials. The chemical composition of the materials used in his works of art is difficult to unravel given that he employed a wide variety of both natural and synthetic organic substances. Analytical pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC-MS) was used to investigate the chemical composition of two works produced in 1950, belonging to the Gobbi and Catrami series of paintings, respectively. The analysis was used to investigate the chemical composition of the paint materials used in these two similar works of art and to highlight any differences in the chemical composition of the paint materials. Analytical pyrolysis was used to identify the chemical composition of the black tar-like materials used in both paintings. Pine pitch was identified in both paintings through the use of Py-GC-MS, while only one painting was characterized by a bituminous material. The molecular composition of the pine pitch gave valuable insights into the type of approach used to produce this material. Various combinations of alkyd paint, drying oil, polysaccharides, triterpenoid resin, and cellulose nitrate were found in the two paintings.

Structural Features of Cork Dioxane Lignin from Quercus suber L.

The dioxane lignin was isolated from extractives- and suberin-free cork (Quercus suber L.) by a modified acidolytic procedure and submitted to structural analysis by permanganate oxidation, analytical pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC-MS), liquid- and solid-state nuclear magnetic resonance (NMR) spectroscopy, and Fourier transform infrared (FTIR) spectroscopy. The molecular weight (Mw = 2500 Da) was assessed by size exclusion chromatography (SEC). The results obtained show that the cork lignin is of syringyl (S)/guaiacyl (G) type with a small proportion of p-hydroxyphenyl (H) units (S:G:H molar ratio of 23:72:5). Among a dozen detected lignin structures, those linked by ether bonds, such as β-O-4' (38 mol %) and 4-O-5' (5 mol %), were the most abundant. The frequency of occurrence of β-5', β-β', 5-5', tetrahydrofuran type, and structures arising from the condensation with concomitant procyanidins was assessed. Ferulates were the only cinnamic structure detected in the cork dioxane lignin.

Selectively Producing Acetic Acid via Boric Acid-Catalyzed Fast Pyrolysis of Woody Biomass

Boric acid is recently proved to be a good substitute for conventional acidic catalytic materials. However, few studies used boric acid as a catalyst in biomass pyrolysis. This study focused on the catalytic effects of boric acid (BA) on pyrolysis behaviors of woody biomass. The birch wood flour (WF) was used as feedstock and treated by impregnation of boric acid solution. Both untreated and boric acid-treated samples (BW) were characterized by FTIR and SEM. Thermogravimetry (TG) and pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC/MS) techniques were used for studying mass loss, composition, and distribution of evolved volatiles formed from pyrolysis process. Additionally, a small fixed-bed pyrolyzer with an amplificated loading amount was used to prepare liquid products, and further, GC/MS were used to analyze the composition of these liquid products. Different pyrolysis temperatures and boric acid/wood flour mass ratios were also studied. The main results are as follows. Boric acid infiltrated into both cell cavity and cell wall through impregnation treatment. FTIR analysis showed that boric acid reacted with wood flour to form B-O-C bond during the treatment. After the treatment of boric acid, the initial degradation temperatures and residual carbon contents were increased, while the maximum weight loss rates were decreased. Boric acid significantly altered the composition and distribution of volatile pyrolysis products of wood flour. It significantly increased the contents of small molecule compounds such as acetic acid and furfural but, decreased the contents of phenol derivatives with high molecular weights. And these changes became more pronounced as the temperature increased. When mass ratio of boric acid (BA) to wood flour (WF) was 2, the acetic acid accounted for 91.28% of the total product in the pyrolysis liquid, which was 14 times higher than that of untreated wood flour. Boric acid effectively catalyzed fast pyrolysis of woody biomass to selectively produce acetic acid

Cellulose Structural Changes during Mild Torrefaction of Eucalyptus Wood.

The changes in the cellulose structure of eight Eucalyptus species (E. botryoides, E. globulus, E. grandis, E. maculata, E. propinqua, E. rudis, E. saligna and E. viminalis) in a mild torrefaction (from 160 °C to 230 °C, 3 h) were studied in situ and after cellulose isolation from the wood by solid-state carbon nuclear magnetic resonance (13C NMR), wide angle X-ray scattering (WAXS), Fourier transform infrared spectroscopy (FTIR) and by analytic pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC/MS). Changes in molecular weight were assessed by viscosimetry. A small decrease in cellulose crystallinity (ca. 2%–3%) was attributed to its amorphization on crystallite surfaces as a result of acid hydrolysis and free radical reactions resulting in the homolytic splitting of glycosidic bonds. The degree of the cellulose polymerization (DPv) decreased more than twice during the heat treatment of wood. It has been proposed that changes in the supramolecular structure of cellulose and in molecular weight during a heat treatment can be affected by the amount of lignin present in the wood. The limitations of FTIR and Py-GC/MS techniques to distinguish the minor changes in cellulose crystallinity were discussed.

Structural changes in lignin of thermally treated eucalyptus wood

Changes in the lignin structure of eight eucalypt species (E. botryoides, E. globulus, E. grandis, E. maculata, E. propinqua, E. rudis, E. saligna, and E. viminalis) upon mild thermal treatment, where the temperature was gradually raised from 160 to 230 °C over 3 h, were studied by solid-state carbon nuclear magnetic resonance (13C NMR) and after lignin isolation from the wood by acidolysis employing liquid-state 1D and 2D NMR techniques. The molecular weight of the isolated lignins was assessed by size exclusion chromatography (SEC) and their composition by analytic pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC/MS). The thermal treatment induced in lignin partial demethylation (up to ca. 30% from total) and a remarkable reduction in β-O-4 structures (up to ca. 60%), in an extent depending on the ratio of syringyl and guaiacyl units of the specific lignins. The lignin molecular weight reduced only ca. 25% under the thermal treatment due to the likely occurrence of condensation reactions by homolytic and heterolytic mechanisms. The noticeable increase in phenylcoumaran (β-5) and pinoresinol/syringaresinol (β-β) structures in lignin after thermal treatment was tentatively explained by their relative thermal resistance and by newly formed structures as the result of radical coupling reactions occurred during homolytic dissociation of the β-O-4 linkages. Lignins in thermally treated wood contained more than twice phenolic hydroxyls and more aliphatic carboxyl groups than lignins in untreated wood.

Selective Production of Acetic Acid via Catalytic Fast Pyrolysis of Hexoses over Potassium Salts

Glucose and fructose are widely available and renewable resources. They were used to prepare acetic acid (AA) under the catalysis of potassium acetate (KAc) by thermogravimetric analysis (TGA) and pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC/MS). The TGA result showed that the KAc addition lowered the glucose’s thermal decomposition temperatures (about 30 °C for initial decomposition temperature and 40 °C for maximum mass loss rate temperature), implying its promotion of glucose’s decomposition. The Py-GC/MS tests illustrated that the KAc addition significantly altered the composition and distribution of hexose pyrolysis products. The maximum yield of AA was 52.1% for the in situ catalytic pyrolysis of glucose/KAc (1:0.25 wt/wt) mixtures at 350 °C for 30 s. Under the same conditions, the AA yield obtained from fructose was 48% and it increased with the increasing amount of KAc. When the ratio reached to 1:1, the yield was 53.6%. In comparison, a study of in situ and on-line catalytic methods showed that KAc can not only catalyze the primary cracking of glucose, but also catalyze the cracking of a secondary pyrolysis stream. KAc plays roles in both physical heat transfer and chemical catalysis.

Plastics in Heritage Science: Analytical Pyrolysis Techniques Applied to Objects of Design.

The first synthetic polymers were introduced as constituents of everyday life, design objects, and artworks at the end of the 19th century. Since then, the history of design has been strictly connected with the 20th century evolution of plastic materials. Objects of design from the 20th century are today a precious part of the cultural heritage. They raise specific conservation issues due to the degradation processes affecting synthetic polymer-based plastics. Museums and collections dealing with the conservation of design objects and modern materials need to base their conservation strategies on compositional data that reveal the formulations of historical plastics and their decay processes. Specific and specifically optimized analytical tools are thus needed. We employed flash analytical pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC/MS) and evolved gas analysis coupled with mass spectrometry (EGA-MS) to characterize “historic polymeric materials” (HIPOMS) and heritage plastics at the molecular level with high chemical detail. This approach complements non-invasive spectroscopic diagnosis whenever it fails to obtain significant or complete information on the nature and the state of preservation of the materials under study. We determined the composition of several 20th century design objects (1954–1994) from the Triennale Design Museum of Milan (Triennale Milano - Museo del Design Italiano), which for different morphological, chemical, or physical reasons were unsuitable for characterization by non-invasive spectroscopy. EGA-MS proved capable for the study of the different fractions constituting heterogeneous micro-samples and for gaining an insight into their degradation processes from the contextual interpretation of thermal and mass-spectrometric data.

Synthetic materials in art: a new comprehensive approach for the characterization of multi-material artworks by analytical pyrolysis

Modern art materials introduced since the end of XIX century include a large number of formulations of synthetic polymers and pigments, whose degradation processes and best preservation conditions are a major issue in heritage science. Analytical pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC/MS) is widely used for the characterisation of polymeric materials and organic pigments, however the interpretation of the pyrograms obtained from samples containing different analytes is not straightforward. To improve our understanding on how these materials behave in complex matrices, we used evolved gas analysis coupled with mass spectrometry (EGA-MS) and multi shot Py-GC/MS to highlight and analyse the different fractions in a sample from a pop-art made of painted polyurethane (PU) foam. The study represents a proof of concept to evaluate EGA-MS potential in studying composite modern art materials in combination with multi-shot pyrolysis. The aim of the investigation was establishing the composition of the PU formulation, the paint binder and the pigments, thereby contributing to planning the stabilisation and conservation of the object. The polymers and the class of synthetic organic pigments present in the paint were assessed by determining their specific pyrolysis products and through comparisons with data in the literature. EGA-MS analysis provided both thermal and chemical information in one analytical run, so that we could select four temperatures for use in multi-shot Py-GC/MS analysis and thus to selectively study the different fractions evolved at different temperatures. Information on the various components of the mixture was obtained, including additives and organic pigments, separating them on the basis of their different thermal degradation temperatures. The multianalytical approach included also non-destructive ATR-FTIR and enabled us to characterize in detail different synthetic materials: polyether-based polyurethane produced by the polyaddition of 2,6-diisocyanate toluene, hexamethylene diisocyanate and polypropylene glycol, vinyl paint, and a mixture of β-naphthol and mono-azo as pigments. HPLC–DAD and HPLC–ESI–MS analyses confirmed the pigments, and provided a positive identification of two β-naphthols (PO5 and PR1) and two monoazo pigments (PY1 and PY3).

Structural Characterization of Lignin in Four Cacti Wood: Implications of Lignification in the Growth Form and Succulence.

Wood lignin composition strongly depends on anatomical features and it has been used as a marker for characterizing major plant groups. Wood heterogeneity in Cactaceae is involved in evolutionary and adaptive processes within this group; moreover, it is highly correlated to the species growth form. Here we studied the lignin structure from different types of woods in four Cactaceae species with different stem morphologies (Pereskia lychnidiflora, tree/fibrous wood; Opuntia streptacantha and Pilosocereus chrysacanthus, tree/succulent fibrous wood; Ferocactus hamatacanthus, cylindrical stem/dimorphic wood) in order to determine their relationship with the wood anatomy in an evolutionary-adaptive context. Dioxane lignin was isolated and analyzed by pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC/MS), two-dimensional nuclear magnetic resonance spectroscopy (2D-NMR) and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR). The main linkages are the β-O−4′ ether (67–85%), the β-β′ resinol (10–26%) and the β-5′ and α-O−4′ linkages of the phenylcoumaran structures (≤7%). Spirodienone structures have a considerable abundance (5%) in the dimorphic wood of F. hamatacanthus. In addition, low contents (≤3%) of α,β-diaryl ether, α-oxidized β-O−4′ ether and dibenzodioxocin structures were found. The sinapyl- and coniferyl acetates are not part of the wood lignin in any of the studied species. The low (≤5%) γ-acetylation in the F. hamatacanthus and P. chrysacanthus wood lignin is here interpreted as an evidence of a high specialization of the wood elements in the conduction/storage of water. The lignin of the studied Cactaceae is composed predominantly of guaiacyl and syringyl units (S/G: 0.9–16.4). High abundance of syringyl units (62–94%) in three of the four species is considered as a defense mechanism against oxidative agents, it is a very conspicuous trait in the most succulent species with dimorphic wood. Furthermore, it is also associated with ferulates and the herein called γ-acetylated guaiacyl-syringaresinol complexes acting as nucleation sites for lignification and as cross-links between lignin and carbohydrates at the wide-band tracheid-fiber junctions.

Investigating the composition and degradation of wool through EGA/MS and Py-GC/MS

Wool has been the most widely used textile fiber in Europe since the Iron Age. It was largely employed to weave fabrics and clothes, and also for artistic purposes such as producing tapestries. This kind of artworks is among the most fragile of our heritage and is often in bad preservation conditions. Thus, the knowledge on the degradation processes of wool fibers is crucial for conservation issues.In the present study, we tested the potentialities of Pyrolysis coupled with Gas Chromatography and Mass Spectrometry (Py-GC/MS) and Evolved Gas Analysis coupled to Mass Spectrometry (EGA/MS) for the characterization of woolen reference samples, also subjected to artificial ageing, and of historical and archeological samples. The reference sheep wool yarns were prepared with different mordants and dyes, and have been analyzed both after storage in the dark for three years after preparation, and artificially aged for different time intervals and at different relative humidity values. We created a detailed pyrolysis database, evidencing the phenomena occurring with ageing and including camel wool for comparison. The ageing process undergone by the proteinaceous fraction of wool has also been investigated through monitoring specific fragment ions in the EGA profiles. The relevant parameters affecting the degradation process identified in this study match those assessed in previous investigations by different and complementary techniques, thus validating our approach. We proved that the novel approach based on EGA/MS is suitable for quickly assessing the conservation conditions of the woolen yarns and represents an advantage with respect to more time-consuming and complex methods, such as GC/MS or High Performance Liquid Chromatography (HPLC).

Deterioration effects of wet environments and brown rot fungus Coniophora puteana on pine wood in the archaeological site of Biskupin (Poland)

The archaeological site of Biskupin (Poland) is a prehistoric settlement dating to the 8th century BC, situated on a marshy island. Excavations started in 1934 and a considerable number of wooden artifacts were found in the lake water. Unfortunately, during many years of archaeological excavations, wooden remains deposited in the trenches were exposed to degradation and underwent considerable decomposition. Among the main causes of wood degradation, fungi and bacteria were the most destructive ones.The chemical effects induced by fungi and bacteria on wood are not well-known or studied. Here we present the investigation of a set of pine wood samples (Pinus sylvestris) buried in the Biskupin site, with the aim of reproducing the burial conditions of the original archaeological wood. Two monitoring stations (wet peat and lake water) were chosen and the samples were then removed from these burial environments after four and ten years. After removal, the samples were exposed to laboratory-controlled attack by the brown rot fungus Coniophora puteana. The final aim was to evaluate the effects of fungal activity on the wood substrates with different degrees of natural degradation. The study is part of an experiment designed to evaluate the short-term effects of the in situ preservation strategy adopted for the Biskupin archaeological woods.Various techniques were used to assess the physical and chemical degradation of the wood. The morphological changes induced by the exposure to the burial environment and by the action of the fungi were investigated using scanning electron microscopy (SEM). The chemical state of the wood was evaluated by using infrared spectroscopy (FTIR), analytical pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC/MS) and XRD spectroscopy.Fungal action caused the depletion of polysaccharides resulting in mass loss and the FTIR spectra of the wood samples highlighted that cellulose was more degraded with respect to hemicelluloses. This trend correlated with an increase in the relative abundance of furans, which are among the main pyrolysis products of polysaccharides. Fungal attack also induced oxidation of lignin and an increase in the crystallinity index of cellulose, which points towards a preferential metabolisation of amorphous cellulose. The overall results highlighted that the burial in these wet environments caused changes mostly in the hemicelluloses, whereas the fungal attack was mainly directed to cellulose degradation.

Aquazol as a binder for retouching paints. An evaluation through analytical pyrolysis and thermal analysis

Aquazol poly (2-ethyl-oxazoline) is a tertiary aliphatic amide, with physical and chemical properties that are exploited in a variety of ways, from pharmaceutical applications to the conservation of cultural heritage. In this study, we evaluated the use of Aquazol as a new binder for retouching paint in the restoration of artworks.Aquazol 500 admixed with various formulations of organic red pigments was used to prepare paint replicas which were artificially aged and investigated by a multi-analytical approach based on analytical pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC/MS), and thermogravimetry (TG), complemented by FTIR and LIBS spectroscopy. This is the first study on the ageing phenomena of Aquazol 500 using analytical pyrolysis and thermogravimetric analysis. The influence of the pigments' components on the pyrolysis behavior of Aquazol was also investigated.The paint replicas did not show significant modifications during artificial ageing. This thus highlights the optimal properties of Aquazol 500 as a binder for retouching, in addition to its already established suitability as a filler or consolidant in the restoration of artifacts. Interestingly, when Aquazol 500 is used in formulations containing organic pigments, Aquazol-pigment interactions are observed, strongly depending on the pigment used.

An investigation into the curing of urushi and tung oil films by thermoanalytical and mass spectrometric techniques

Urushi is the oldest and most precious lacquer used since antiquity in East Asia. For artistic purposes, in order to obtain suitable rheological properties, the lacquer is usually mixed with a vegetable oil. In this work we investigated the curing process of urushi/tung oil mixtures in order to highlight the chemical interactions at the molecular level between the two materials.A multi-analytical approach was adopted, based on thermogravimetry (TG), differential scanning calorimetry (DSC), gas chromatography-mass spectrometry (GC-MS), evolved gas analysis-mass spectrometry (EGA-MS), analytical pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC-MS) and high performance liquid chromatography-mass spectrometry (HPLC-MS). Fresh and aged mixtures were analysed and the results were compared with those obtained from the analysis of the individual materials.The data highlighted that different polymerisation and oxidation mechanisms take place in oil/urushi mixtures compared to the pure materials. Py-GC-MS and GC-MS showed that the profile of aliphatic mono- and di-carboxylic acids was drastically different for the aged film of pure tung oil compared to the mixtures. The ratio between the relative content of azelaic and palmitic acids was much lower in the mixtures than in the pure oil, highlighting a lower level of oxidation. On the other hand, the relative content of short chain carboxylic acids, which are produced by pyrolysis of the cross-linked oil network, increased as the concentration of urushi in the mixtures increased, thus indicating an increasing level of reticulation. HPLC-MS showed a relatively higher amount of triglycerides with hydroxylated fatty acids – the intermediate oxidation product of polyunsaturated fatty acids - in the mixtures with respect to pure tung oil.

Isolation and Structural Characterization of Lignin from Cardoon (Cynara cardunculus L.) Stalks

The lignin from Cynara cardunculus stalks was isolated by the classical Bjorkman method and characterized by pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC/MS), two-dimensional nuclear magnetic resonance spectroscopy (2D-NMR), and derivatization followed by reductive cleavage (DFRC). The milled Cynara lignin (MCyL) was constituted mainly by guaiacyl (G) and syringyl-units(S) (S/G molar ratio of 0.7), with the complete absence of p-hydroxyphenyl (H) units. The 2D-NMR analysis indicated a predominance of alkyl-aryl ether linkages (70 % of all inter unit linkages are β–O–4′) and significant amounts of condensed structures such as phenylcoumarans (β-5′, 14 %), resinols (β-β′, 7 %), spirodienones (β-1′, 5 %), and dibenzodioxocins (5-5′, 4 %). Furthermore, the analyses indicated that the lignin is partially acylated at the γ-OH (12 % acylation) by acetate groups and that acetylation occurs preferentially on syringyl-units. As in other plants, acetylation occurs at the monomer stage, and sinapyl acetate behaves as a real lignin monomer participating in lignification in cardoon stalks. The detailed structural characterization of cardoon lignin reported here will foster the industrial use of this biomass for the production of biofuels and other bio-based chemicals under the lignocellulosic biorefinery.

Archaeological wood degradation at the site of Biskupin (Poland): Wet chemical analysis and evaluation of specific Py-GC/MS profiles

Eight samples of ca. 3000 year old oak wood from the Biskupin site and a piece of sound oak (Quercus sp.) wood were analysed. The degradation state of archaeological oak wood was investigated using two analytical approaches: classical wet chemical analysis and analytical pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC/MS) with in situ silylation. The results were compared with those obtained for sound oak wood.Chemical analysis provided information on the amount of wood components. Their alteration at a molecular level was investigated by Py-GC/MS, highlighting how degradation can affect the formation of primary and secondary wood pyrolysis products.The results showed that the chemical changes in the wood material in the eight samples examined had different entities and extents with comparison to sound oak wood. Samples taken from the external parts of the fragments had undergone a significant loss in polysaccharide components, whereas the internal parts were in a relatively good state of preservation. Evaluation of the relative amounts of pyrolysis products deriving from holocellulose and lignin highlighted that specific categories of compounds, such as lignin monomers and anhydrosugars, can be taken as an index for good preservation of wood components.These results will be used to evaluate the effectiveness of the in situ conservation strategy by repeating the analyses on these samples after some years and comparing the results.

In situ determination of the syringyl/guaiacyl ratio of residual lignin in pre-bleached eucalypt kraft pulps by analytical pyrolysis

Pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC/MS) was used for evaluating the syringyl/guaiacyl (S/G) ratios of residual lignins in oxygen pre-bleached kraft pulps from 24 Eucalyptus wood clones. The optimization of the method showed that the best conditions were achieved when pyrolysis is carried out at 550°C, using a 60m length SPB-1701 capillary column and the mass spectrometer operating in SIM mode. Pulp pyrograms were analyzed and the compounds produced by pyrolysis of residual lignins identified by mass spectrometry. A total of 18 compounds were identified, being nine derived from guaiacyl units and nine derived from syringyl lignin. The S/G ratios were calculated using the relative area of S-lignin (syringol, 4-methylsyringol, 4-vinylsyringol and trans-4-(prop-2-enyl) syringol) and G-lignin (guaiacol, 4-methylguaiacol, 4-vinylguaiacol and trans-isoeugenol) as lignin markers. These studies showed that Py-GC/MS-SIM is an efficient tool to characterizing the chemical composition of residual lignin in oxygen pre-bleached Eucalyptus pulps.

Microscopic techniques (LM, SEM) and a multi-analytical approach (EDX, FTIR, GC/MS, Py-GC/MS) to characterise the decoration technique of the wooden ceiling of the House of the Telephus Relief in Herculaneum (Italy)

The House of the Telephus Relief in Herculaneum (Naples, Italy) is a Roman domus, buried by the eruption of Mount Vesuvius in AD 79. The house had a wooden roof with decorated ceiling, which was discovered in 2009. The roof represents an extraordinary archaeological find and, although it was found mainly disassembled, some of its wooden decorative panels are still almost intact. Some portions of the original polychrome decoration and traces of gilding are still preserved.Within the framework of the Herculaneum Conservation Project, a diagnostic study was undertaken to characterise the materials used in the polychrome decoration and to assess the technique used by Roman painters to decorate the ceiling.Micro samples (c. 500μg) of paint were analysed with a multi-analytical approach. The micro-morphological characterisation of the pigments and the paint stratigraphy was assessed using light (LM) and scanning electron microscopes (SEM). X-ray microanalysis (EDX) coupled with SEM and Fourier transform infrared spectroscopy (FT-IR) were used to investigate the inorganic components. Gas chromatography/mass spectrometry (GC/MS) and pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC/MS) were used to identify the binding media and other organic materials. The nature of the sediment, where the findings had been embedded, was also investigated.The acquired data revealed that a tempera painting has been applied. Egg was used as binder, whereas lime, red and yellow ochre, and caeruleum were used as white, red, yellow and blue pigments, respectively. The paint was directly applied onto the wood surface. Some decorations involved the application of gold leaf: unfortunately, no trace of the mordant or adhesives was found. The results also highlighted some issues related to the state of preservation of the artefact, thus contributing to the planning of conservation strategies.