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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.

This review describes the capability of analytical pyrolysis-based techniques to provide data on lignin composition and on the chemical alteration undergone by lignin in archaeological wooden objects. Applications of Direct Exposure Mass Spectrometry (DE-MS), Evolved Gas Analysis Mass Spectrometry (EGA-MS), and single and double-shot Pyrolysis-Gas Chromatography/Mass Spectrometry (Py-GC/MS) in archaeological lignin characterisation are described. With comparison to cellulose and hemicelluloses, lignin is generally less prone to most degradation processes affecting archaeological artefacts in burial environments, especially waterlogged ones, which are the most favourable for wood preservation. Nevertheless, lignin also undergoes significant chemical changes. As wood from waterlogged environments is mainly composed of lignin, knowledge of its chemical structure and degradation pathways is fundamental for choosing preventive conservation conditions and for optimising consolidation methods and materials, which directly interact with the residual lignin. Analytical pyrolysis coupled with mass spectrometry, used in several complementary operational modes, can gather information regarding the chemical modifications and the state of preservation of lignin, especially concerning oxidation and depolymerisation phenomena. Several applications to the analysis of wood from archaeological artefacts affected by different conservation problems are presented to showcase the potential of analytical pyrolysis in various scenarios that can be encountered when investigating archaeological waterlogged wood. [ABSTRACT FROM AUTHOR]

Abstract: The molecular characterization of organic materials in samples from artworks and historical objects traditionally entailed qualitative and quantitative analyses by HPLC and GC. Today innovative approaches based on analytical pyrolysis enable samples to be analysed without any chemical pre‐treatment. Pyrolysis, which is often considered as a screening technique, shows previously unexplored potential thanks to recent instrumental developments. Organic materials that are macromolecular in nature, or undergo polymerization upon curing and ageing can now be better investigated. Most constituents of paint layers and archaeological organic substances contain major insoluble and chemically non‐hydrolysable fractions that are inaccessible to GC or HPLC. To date, molecular scientific investigations of the organic constituents of artworks and historical objects have mostly focused on the minor constituents of the sample. This review presents recent advances in the qualitative and semi‐quantitative analyses of organic materials in heritage objects based on analytical pyrolysis coupled with mass spectrometry. [ABSTRACT FROM AUTHOR]

Wood artefacts undergo complex alteration and degradation during ageing, and gaining information on the chemical composition of wood in archaeological artefacts is fundamental to plan conservation strategies. In this work, an integrated analytical approach based on innovative NMR spectroscopy procedures, gel permeation chromatography and analytical pyrolysis coupled with gas chromatography/mass spectrometry (Py-GC-MS) was applied for the first time on archaeological wood from the Oseberg collection (Norway), in order to evaluate the chemical state of preservation of the wood components, without separating them. We adopted ionic liquids (ILs) as non-derivatising solvents, thus obtaining an efficient dissolution of the wood, allowing us to overcome the difficulty of dissolving wood in its native form in conventional molecular solvents. Highly substituted lignocellulosic esters were therefore obtained under mild conditions by reacting the solubilised wood with either acetyl chloride or benzoyl chloride. A phosphytilation reaction was also performed using 2-chloro-4,4,5,5-tetramethyl-1,3,2-dioxaphospholan. As a result, the functionalised wood developed an enhanced solubility in molecular solvents, thus enabling information about modifications of lignin, depolymerisation of cellulose and structure of lignin-carbohydrate complexes to be obtained by means of spectroscopic (2D-HSQC-NMR and P-NMR) and chromatographic (gel permeation chromatography) techniques. Py-GC-MS was used to investigate the degradation undergone by the lignocellulosic components on the basis of their pyrolysis products, without any pre-treatment of the samples. The application of all these combined techniques enabled a comprehensive characterisation of the whole cell wall of archaeological wood and the evaluation of its state of preservation. High depletion of carbohydrates and high extent of lignin oxidation were highlighted in the alum-treated objects, whereas a good preservation state was found for the untreated wood of the Oseberg ship. [ABSTRACT FROM AUTHOR]

Historically, a very large variety of everyday artifacts were made of wood, which makes them representative of their historical period or social context and valuable for archaeologists and historians. In order to preserve degraded wood and to develop and apply suitable conservation treatments, chemical and physical characterization of archaeological wood is needed. This review provides the reader with a survey on state-of-the-art of instrumental analytical tools available to understand the morphology and the chemical composition of archaeological wood. The focus is on microscopic and spectroscopic techniques such as scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), Raman, nuclear magnetic resonance (NMR) and analytical techniques based on pyrolysis, such as direct exposure–mass spectrometry (DE-MS), pyrolysis–mass spectrometry (Py-MS), pyrolysis–gas chromtography–mass spectrometry (Py-GC/MS), with emphasis on their respective potentialities and limitations. The advantages of techniques based on synchrotron radiation are also discussed. In addition, the applicability of each examined technique is illustrated and discussed through specific examples from the literature. [ABSTRACT FROM AUTHOR]

Abstract: Two techniques based on analytical pyrolysis and mass spectrometry, direct exposure-MS (DE-MS) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), were used to characterise waterlogged archaeological wood and to study degradation patterns of wood in aqueous environments. The two techniques were applied to samples from the excavation of the Site of the Ancient Ships of Pisa San Rossore in Pisa (Italy), and data were compared to those relative to native sound wood of the same species (pine, elm, beech). Both the methods result valuable in the analysis of ancient wood artefacts, avoiding the long wet-chemical procedures that are commonly used in wood analysis, and allowing us to use a minimal sample size. DE-MS achieves a global mass spectral fingerprint of lignin and polysaccharides pyrolysis compounds in few minutes, and the results have been interpreted with the support of principal component analysis (PCA) of mass spectra. Py-GC/MS permits detailed molecular analysis of pyrolysis compounds and highlights some chemical modifications of lignin in archaeological samples, as demethylation of both guaiacyl and syringyl lignin units. Both the techniques demonstrate consistent loss of polysaccharides in archaeological wood. [Copyright &y& Elsevier]

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). [ABSTRACT FROM AUTHOR]

Chemically evaluating the state of preservation of archaeological wood in the presence of consolidating agents, such as polyethylene glycol (PEG), can be challenging. Interpreting the results obtained by the most commonly used single-shot pyrolysis method coupled with gas chromatography and mass spectrometry with in situ silylation (Py(HMDS)-GC/MS) is complicated, since both wood and PEG pyrolysis products are produced and poorly separated by GC. Two new approaches based on analytical pyrolysis are here applied for the first time to consolidated archaeological wood in order to obtain information on both the degraded wood and the consolidating material. Evolved gas analysis mass spectrometry (EGA-MS) provided information on the thermal stability of the materials, as well as on the distribution of the pyrolysis products. The results showed that, for some archaeological wood samples, wood and PEG can be thermally separated. A double-shot Py(HMDS)-GC/MS procedure was also tested and the pyrolysis temperatures for the two shots were chosen on the basis of EGA-MS results. The pyrolysis products of wood and PEG were separated into two different pyrograms. In some cases, the combination of EGA-MS and double-shot Py(HMDS)-GC/MS provided more detailed information on the material degradation compared to single-shot Py(HMDS)-GC/MS. [ABSTRACT FROM AUTHOR]

Abstract: A combination of analytical pyrolysis with gas chromatography and mass spectrometry (Py-GC/MS) was used to study the chemical composition and level of decay of wood objects from the historical site of the Wieliczka salt mine (Poland). The site has been on UNESCO''s First World List of Cultural and Natural Heritage since 1978. The wood is located underground in the form of structures supporting the roofs and walls, as well as machines and mining equipment. It has been gradually saturated with rock salt (sodium chloride) over tens and hundreds of years. The presence of numerous metallic connections has significantly contributed to the destruction of the wood artifacts. Iron under conditions of high salinity is subjected to processes of electrochemical corrosion and produces compounds that penetrate wood, accelerating its degradation. The results have been interpreted with the support of principal component analysis (PCA). The chemometric evaluation of the Py-GC/MS data contributed to an understanding of the chemical differences and similarities between the samples. [Copyright &y& Elsevier]

Abstract: The macromolecular complexity of wood limits the possibility of obtaining complete chemical information on its alteration in archaeological objects. This paper compares the results obtained in the characterisation of the components of archaeological wood by a classical wet chemical method and by an instrumental method based on pyrolysis in presence of hexamethyldisilazane coupled with gas chromatography/mass spectrometry, Py(HMDS)–GC/MS. We compare the results obtained with the two methods quantitatively. This enables us to evaluate the efficiency of Py(HMDS)–GC/MS in assessing the chemical composition and the state of conservation of degraded wood. The material analysed consisted of reference sound wood and waterlogged wood from the Żółte historical site, located on a small island on Lake Zarańskie in Poland. The samples are from the remains of settlements dating to a period between the 9th and the 12th centuries AD. The results obtained by Py(HMDS)–GC/MS analysis are consistent in the determination of the level of degradation of archaeological wood with the results obtained using traditional techniques. The pyrolysis method is faster, reproducible, and reveals not only the amount but also the quality of the wood constituents, needing a much smaller sample. [Copyright &y& Elsevier]

Highlights • Study of a polyurethane pop-art sculpture by FTIR and pyrolysis based techniques. • Application of evolved gas analysis mass spectrometry and double shot pyrolysis-GC/MS. • Evaluation of degradation pathways of polyurethane foam after 50 years of natural ageing. Abstract Specific analytical tools are needed to investigate the composition and degradation processes of the synthetic materials in the cultural heritage, and recent advancements in pyrolysis-based analytical techniques have great potential for the characterisation of synthetic polymers. We applied evolved gas analysis mass spectrometry (EGA-MS) and double shot pyrolysis coupled with chromatography and mass spectrometry (Py-GC/MS) to investigate polyurethane foam micro-samples from the Italian pop-art sculpture “Contenitoreumano n.1” (1968) by Ico Parisi (1916–1996) and Francesco Somaini (1926–2005). The chemical analysis aimed to assess the chemical composition and of the state of preservation of the PU foam by acquiring information on its thermal degradation behaviour and identifying the pyrolysis products produced at different temperatures. A preliminary ATR-FTIR analysis was also carried out. The multi-analytical approach enabled us to identify the isocyanate and polyol precursors as 2,6-toluenediisocyanate and polypropylene glycol, respectively. The plasticizers used in the production of the PU foam were also identified in the first shot of a double shot Py-GC/MS experiment. A comparison of a sample of better preserved foam with a sample of degraded foam from the surface of the object highlighted that the more degraded part of the PU foam featured an increase in the thermal degradation temperature of the soft-fragments of the PU network, related to cross-linking phenomena. Moreover, loss of plasticizers and formation of NH2 functional groups was observed in the degraded foam. [ABSTRACT FROM AUTHOR]

Cellulosic pulp was analysed after two and five years of natural ageing in two different burial environments - lake water and peat soil - in order to investigate the chemical and structural changes undergone by the material. This research is part of a monitoring program developed in the archaeological site of Biskupin, whose final aim is to estimate the best re-burial conditions for an in situ conservation of archaeological wood. We applied SEM, FT-IR, XRD and Py-GC/MS with thermally assisted silylation using hexamethyldisilazane (HMDS) to obtain broad information on cellulosic pulp degradation. SEM provided information on the structural changes undergone by the fibres and on the microbial activity. FT-IR highlighted a depletion of the carbohydrates in the most degraded samples. Py(HMDS)-GC/MS confirmed these observations and provided detailed molecular information on cellulose alteration. The crystallinity index (CI) of cellulose was estimated by XRD, showing that the degradation began in amorphous regions. The correlation between the CI and the relative abundance of anhydrosugars detected by Py(HMDS)-GC/MS demonstrated that pyrolytic reactions are also influenced by the degree of crystallinity of cellulose. A mechanism of cellulose degradation in these natural environments was formulated: the degradation of cellulose in these natural environments proceeds through a depolymerisation step, initially involving the amorphous regions of cellulose, until the size of oligomers becomes sufficiently small to allow metabolisation by microorganisms or solubilisation by water. Secondly, a loss of carbohydrates was detected after five years of ageing and the loss reached 25% and 55% for the dark areas of samples aged in peat soil and lake water, respectively. Peat soil was found to be more suitable than lake water in terms of preservation of carbohydrates. [ABSTRACT FROM AUTHOR]

The paint materials in three different Keith Haring outdoor murals, Tuttomondo in Pisa (1989), the Necker Hospital mural in Paris (1987), and the Melbourne mural (1984), were investigated using pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). The aim of the study was to characterize the chemical composition of the paint materials used by the artist in the three mural paintings and to correlate their chemical composition to their state of conservation. The analyses were performed using a PY-3030D pyrolyzer (Frontier Lab, Japan). The analyses of the paint samples from Tuttomondo showed the presence of a styrene/ n -butylacrylate copolymer, which had been used as a paint binder. The results were then compared with those obtained with a Pyroprobe 5000 pyrolyzer (CDS Analytical, U.S.A.). The pyrolysis profiles of the paint samples of the Paris mural were characterized by the presence of benzene and acetic acid, together with small amounts of toluene, styrene, indene, and different aromatic compounds, which indicated the presence of a vinyl resin. The various isomers of the vinyl ester of versatic acid were attributed to VeoVa TM , present in the vinyl polymer as an internal plasticizer. In the Melbourne mural, there was a high heterogeneity of paint materials, both original and deriving from a restoration intervention. The Py-GC/MS analyses revealed the presence of alkyd, vinyl, and acrylic resins. The samples were collected within the framework of conservation campaigns carried out on the three artworks. The results enabled the materials used by the artist to be identified, and highlighted the conservation state of the murals. They also provided conservators and restorers with helpful information for the choice of cleaning and protection procedures. Having access to three different examples of Haring's street art enabled us to compare the paint techniques and to relate them to the state of conservation. [ABSTRACT FROM AUTHOR]

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. • Py-GC-MS was used for the characterization of the paint materials of two Burri's works of art. • The analysis allowed us to identify the presence of both natural and synthetic paint materials. • Py-GC-MS allowed us to differentiate between pine pitch and bituminous material. [ABSTRACT FROM AUTHOR]

Historical airplanes have entered museum collections to show the development of aviation and are part of our technical heritage. The period between the 1920′s and 1945 is characterized by giant progressions in the chemical industry. During these years a wide increase in the production of new materials and solvents was observed, that replaced the natural materials used in the aircraft industries due to their improved properties. In Germany this industrial development was counteracted by preparations for the war that aimed at a self-sufficiency based on German products and thus an independency of the international market. This work presents the analyses of the organic binders of painted layers of a Messerschmitt Bf 109 model E-3 used until the 1955 and repainted several times until the 1974 and a cabin roof from a Bf 109 model B built in the 1937–1938 lost during the flight and never repainted. The microscopic analyses performed on the samples from the two planes allowed us to characterize the presence of a high and variable number of paint layers. These layers adhere extremely well on each other and are very brittle. For this reason, it was almost impossible to separate them for analytical purposes by mechanical means. In this study we applied for the first time analytical pyrolysis coupled with gas chromatography and mass spectrometry for the characterization of the painted layers from the two planes. The combination of the versatility of analytical pyrolysis together with the high selectivity of gas chromatography and mass spectrometry allowed us to fully characterize and discriminate the synthetic and natural materials used in both airplanes, and to characterize the original paint binders as being composed of alkyd resin, phenol formaldehyde resin and nitrocellulose. • Py-GC-MS was used for the study the aircraft paints of two Messerschmitt Bf 109. • We compare the results of a cabin roof of 1938 with those of a plane restored until 1974. • We detect up to six different materials in the same paint sample. • We compare the results with the intelligence information available during Second World War. [ABSTRACT FROM AUTHOR]

Abstract: This paper focuses on the chemical characterization of samples of black decorations and inscriptions, and of yellow-brown patinas collected from various panels of the ark from the chapel of Saint Anthony (Padua, Italy), using three analytical procedures based on gas chromatography/mass spectrometry (GC/MS). Analytical pyrolysis in the presence of hexamethyldisilazane followed by gas chromatographic–mass spectrometric analysis (Py-GC/MS) and two procedures based on gas chromatography/mass spectrometry after wet-chemical treatment of the samples (GC/MS) were chosen for the recognition of the organic substances (used originally or in the course of restoration) and of their degradation products. In terms of the two GC/MS procedures, one was used to characterize proteins, lipids, resins, waxes, bituminous materials and their degradation products, and the other to characterize saccharide materials. The three analytical procedures used enabled us to obtain information on the presence of egg proteins, lipid materials (beeswax, siccative oil and animal fatty material), saccharide materials and Pinaceae resin. Beeswax, animal fat, egg and saccharide materials have been used in the past as restoration materials, and pine resin and siccative oil were the main ingredients in the black decorations and inscriptions. [Copyright &y& Elsevier]

• Pyrolysis and thermal analysis have potential to become of general use to study MPs. • The review describes the state-of-the-art of MPs analysis by thermal techniques. • We provide a comprehensive critical examination of recent quantitative analysis developments. • Main analytical issues and limitations are described with practical detail. • The review contributes to evaluate analytical techniques and analytical data in MP research. Environmental pollution from microplastics (MPs) and the associated health and environmental risks are the focus of intense multidisciplinary research. In fact, that there is an urgent need to produce quantitative and qualitative data on the amount and types of MPs in environmental matrices, organisms, and commodities, and to perform spatial and temporal comparisons. This has led to the development, optimization and application of analytical methods to characterize MPs in aquatic, terrestrial or biological samples. Instrumental analytical techniques based on analytical pyrolysis and thermal analyses provide qualitative and mass-based quantitative information and have a high potential to become of general use in the analysis of MPs. This paper reviews the research carried out to date in the analysis of MPs by analytical thermal and pyrolysis techniques. The aim is to provide a detailed and comprehensive critical examination of recent quantitative analysis developments, integrated with a brief historical excursus. The main analytical issues and limitations are described with practical detail, to provide an overview of the rapid ongoing development of this sector of analytical chemistry, and to contribute to the activities aimed at evaluating, comparing and standardising analytical techniques and analytical data in MP research. [ABSTRACT FROM AUTHOR]