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• We present a shortcut in the compositional analysis of plastic waste. • The separation system's influence on the homogeneity and performance is examined. • Both HDPE samples display good material performance and a homogeneous composition. • PP and LDPE from post source separation display slightly more heterogeneity. • Multivariate FTIR data evaluation is a fast and informative analysis method. Whether plastic packaging waste is disposed of in different bins (source separation, S) or in a single bin (post source separation, P) is generally assumed to impact the waste stream's quality. To elucidate this question, we evaluated the quality of LDPE, HDPE, and PP plastic waste from both separation systems (S and P) through a concise analytical strategy. The materials received similar treatment after collection (e.g., washing, NIR-sorting). A multivariate approach to ATR-FTIR spectroscopy was developed to assess their material composition and the effect of washing. Results were complemented by TGA, DSC, and py-GC/MS analysis. The material performance was investigated by a lab-scale extrusion and granulation, followed by an assessment of the mechanical properties and the melt volume rate. Our study reveals the HDPE materials to be of good quality, regardless of their source. For LDPE and PP, the P-materials are fractionally more contaminated after washing. Both PP-materials display poor material performance with highly fluctuating elongations-at-break (between 30 % and 380 %). S-LDPE was found to contain more polymeric impurities than P-LDPE. We conclude that the quality depends strongly on the material type and on the treatment after collection (washing, sorting). The multivariate approach to FTIR data evaluation we propose aims at simplifying the quality evaluation of polyolefin waste plastics and may serve as a basis for future work in this field. [ABSTRACT FROM AUTHOR]

Erythrina crista-galli is commonly used in folk medicines for its pharmacological properties which are associated with the bioactive compounds. Profiling botanical parts of E. crista-galli is an exciting topic and essential to uncover the similarity and clustering based on their chemical content. The botanical parts of E. crista-galli, including bark, flowers, leaves, roots, and twigs, were subjected to pyrolysis-gas chromatography/mass spectrometry. The samples were pyrolyzed using a multi-shot pyrolyzer. The relative abundance of the pyrolysate was subjected to multivariate analysis, i.e., principal component analysis (PCA) and hierarchical cluster analysis (HCA). The scree plot for PC.1, PC. 2, and PC. 3 accounted for 36.5%, 27.2%, and 20.3%, respectively. Together, the first three PCs explain 84% of the total variance. The PCA allows characterizing the roots of E. crista-galli by the highest relative abundance of lignin G, followed by the twigs, bark, and leaves, while the flowers had the least relative abundance of lignin G. The HCA allows to cluster the botanical parts of E. crista-galli into three different clusters based on their chemical component similarity, i.e., flowers-leaves, twigs, and roots-bark. In conclusion, Py-GC/MS analysis can be used in conjunction with multivariate data analysis to characterize the botanical parts of E. crista-galli.

Nitrogen can be taken up by trees in the form of nitrate, ammonium and amino acids, but the influence of the different forms on tree growth and development is poorly understood in angiosperm species like Populus. We studied the effects of both organic and inorganic forms of nitrogen on growth and wood formation of hybrid aspen trees in experimental conditions that allowed growth under four distinct steady‐state nitrogen levels. Increased nitrogen availability had a positive influence on biomass accumulation and the radial dimensions of both xylem vessels and fibers, and a negative influence on wood density. An optimal level of nitrogen availability was identified where increases in biomass accumulation outweighed decreases in wood density. None of these responses depended on the source of nitrogen except for shoot biomass accumulation, which was stimulated more by treatments complemented with nitrate than by ammonium alone or the organic source arginine. The most striking difference between the nitrogen sources was the effect on lignin composition, whereby the abundance of H‐type lignin increased only in the presence of nitrate. The differential effect of nitrate is possibly related to the well‐known role of nitrate as a signaling compound. RNA‐sequencing revealed that while the lignin‐biosynthetic genes did not significantly (FDR <0.01) respond to added NO3−, the expression of several laccases, catalysing lignin polymerization, was dependent on N‐availability. These results reveal a unique role of nitrate in wood formation and contribute to the knowledge basis for decision‐making in utilizing hybrid aspen as a bioresource. [ABSTRACT FROM AUTHOR]

Composting is recognized as a sustainable waste management strategy. However, little is known about green waste, and specifically rose waste, degradation patterns during composting. This study aimed (1) to gain insight in the underlying decomposition patterns during rose waste composting and (2) to identify co-metabolisms of ligneous material. Five different compost mixtures were tested ranging from pure rose waste to mixtures with tomato waste, kalanchoe waste or mature compost added. Samples were taken during a six-month experiment and analyzed by pyrolysis-GC/MS. The temporal trends in the relative abundance of 10 different compound groups were measured. Lignin and aliphatic compounds together accounted for ≥ 50% of the quantified pyrolysis products, but with changing contributions during composting. The relative abundance of polysaccharides and terpenes strongly decreased with more than 60% in the first 2 months. The simultaneous decrease in relative abundance of lignin and polysaccharides during initial composting phase indicated co-metabolism of lignin. The results from this study showed that while the presence of lignin is commonly regarded as a challenge in composting, it actually undergoes degradation through distinct mechanisms at the various composting stages. [ABSTRACT FROM AUTHOR]

Factors controlling organic carbon stabilization are elusive in neutral-to-alkaline soils, thereby hindering the assessment of carbon sequestration potential across vast agricultural regions like the Indo-Gangetic Plain (IGP). This study investigated controls over mineralization and stabilization of added organic matter in tropical neutral-to-alkaline soils with low organic carbon (SOC). Using topsoil and subsoil samples from 12 sites of upper-to-lower IGP, we conducted a one-year incubation with and without adding 13C-labeled maize material. We tracked CO2 release and residual C remaining in soil organic matter fractions (free, occluded particulate (oPOM), and mineral-associated organic matter (MAOM)) and analyzed organic matter molecular compositions in incubated soils using pyrolysis-GC/MS. Our results revealed that 48 ± 7 % of added maize C was mineralized, mostly within the first 70 days. Higher active Al/Fe, notably Al, retarded primary maize mineralization by facilitating aggregation. High SOC content and SOC saturation degree resulted in more maize mineralization. The disappearance of maize-unique compounds (e.g., neophytadiene) revealed substantial degradation of added maize. Regarding SOC composition, maize addition increased the relative abundance of fatty acids and decreased that of N-containing compounds. Most residual maize-derived C was found in stabilized fractions, MAOM (77 ± 15 % of residual maize C) and oPOM (8 ± 4 %). Clay fraction contributed to most maize-derived C stabilization as MAOM (path coefficient (β) = 0.81**). Moreover, the significant correlation (P

Microplastics (MPs) the products of plastic breakdown, are entering the environment as a result of plastic abuse, which are of size less than 5mm. Due to their ubiquitous nature, MPs have become a significant environmental concern. One alarming area of MPs contamination is their potential presence in the feed of edible animal species. Growing research suggests that MPs can enter food products and subsequently move to various trophic levels of food chains. Hence, assessing the threat of MPs contamination in animal feed is important for food security and human health. In this investigation, 36 livestock and poultry feed samples were collected from 12 different farms, MPs were detected using Fourier Transform Infrared Spectroscopy (FTIR) and Differential Scanning Calorimeter (DSC). The Nano particle analyser was used to determine the size distribution, and Pyrolysis-GC/MS was used to quantify MPs. According to the findings, all the feed samples contained a significant amount of Polyethylene terephthalate (PET), Polypropylene (PP), and Polyvinyl chloride (PVC) and the particle size ranged from 2.02 to 10.7 µm. Present study has given detailed information on the size distribution of MPs in animal feed, which is thought to enable them to pass through membrane barriers. From the findings it is evident that there are high chances of MPs entering animal feed due to the continuous contact of the feed with plastic-based materials. These MPs can accumulate in the tissues of animals and potentially be transferred to humans through the consumption of meat, milk, and other animal-derived products. Subsequently these MPs can finally bio-accumulate in humans and cause serious health issues. [ABSTRACT FROM AUTHOR]

Thermal characterization of kraft lignin (KL) prepared from mixed hardwoods was conducted to determine their thermal and thermo-oxidative stability, glass transition temperature (Tg), pyrolysis products composition, and syringyl/guaiacyl ratio. Two milled wood lignins (MWLs) from acacia (MWL-aca) and mixed hardwoods (MWL-mhw), the same hardwood species employed in the production of KL, were also characterized for comparison with KL. Thermogravimetric analysis (TGA) indicated that KL had higher thermal and thermo-oxidative stability than MWLs. Based on differential scanning calorimetry (DSC), the Tg of KL was 63.2 °C, while MWLs gave similar values near 165 °C. The syringyl (S), guaiacyl (G), p-hydroxyphenyl (H) composition of KL acquired from pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) at 675 °C was 48:44:8 (S/G ratio 1.07), while MWL-aca and MWL-mhw were 31:60:9 and 46:48:6, respectively.

The total mass of individual synthetic polymers present as microplastic (MP < 2 mm) pollutants in the sediments of interconnected aquatic environments was determined adopting the Polymer Identification and Specific Analysis (PISA) procedure. The investigated area includes a coastal lakebed (Massaciuccoli), a coastal seabed (Serchio River estuarine), and a sandy beach (Lecciona), all within a natural park area in Tuscany (Italy). Polyolefins, poly(styrene) (PS), poly(vinyl chloride) (PVC), polycarbonate (PC), poly(ethylene terephthalate) (PET), and the polyamides poly(caprolactame) (Nylon 6) and poly(hexamethylene adipamide) (Nylon 6,6) were fractionated and quantified through a sequence of selective solvent extractions followed by either analytical pyrolysis or reversed-phase HPLC analysis of the products of hydrolytic depolymerizations under acidic and alkaline conditions. The highest concentrations of polyolefins (highly degraded, up to 864 µg/kg of dry sediment) and PS (up to 1138 µg/kg) MPs were found in the beach dune sector, where larger plastic debris are not removed by the cyclic swash action and are thus prone to further aging and fragmentation. Surprisingly, low concentrations of less degraded polyolefins (around 30 µg/kg) were found throughout the transect zones of the beach. Positive correlation was found between polar polymers (PVC, PC) and phthalates, most likely absorbed from polluted environments. PET and nylons above their respective LOQ values were found in the lakebed and estuarine seabed hot spots. The pollution levels suggest a significant contribution from riverine and canalized surface waters collecting urban (treated) wastewaters and waters from Serchio River and the much larger Arno River aquifers, characterized by a high anthropogenic pressure. [ABSTRACT FROM AUTHOR]

Carbohydrates are a ubiquitous constituent of organisms and contribute significantly to sedimentary organic carbon pools. Yet, the factors that control the degradation and long-term preservation of sedimentary carbohydrates are not well understood. Here, we investigate carbohydrate pool sizes and chemical compositions in high-altitude, meromictic Lake Cadagno (Switzerland) over a 13,500-year-old sedimentary succession that has recorded past changes from oxic to anoxic conditions and consists mostly of intercalations of lacustrine sediments and terrestrial-derived sediments. Analyses of the organic matter chemical composition by pyrolysis gas chromatography/mass spectrometry (Py-GC/MS) show that carbohydrates are selectively preserved over other organic matter constituents over time. The carbohydrate pyrolysis products levosugars (potentially cellulose-derived) and (alkyl)furans and furanones (potentially pectin-derived) dominate both lacustrine and terrestrially derived sediment layers, suggesting aquatic and terrestrial-derived sources of these compounds. Carbohydrate monomer analyses indicate galactose and glucose as dominant monomers and show no clear differences between aquatic and terrestrial organic matter. No clear impacts of past changes in redox conditions on carbohydrate compositions were observed. Our study shows that carbohydrates are a major contributor to sedimentary organic carbon burial in Lake Cadagno and indicates the effective preservation of both aquatic and terrestrial derived carbohydrates over millennia in lake sediments.

Pyrolysis non-isothermal kinetics, thermodynamics and products compositional characteristics of kitchen wastes fermentation residues (KWFR) were investigated to explore the bioenergy potential by thermogravimetric analysis and pyrolysis gas chromatography mass spectrometry (Py-GC/MS) methods. The results showed that pyrolysis process can be divided into four common stages. The kinetics results deduced from FWO, KAS and Popescu methods showed that reaction activation energy (E) was 170.56, 168.98 and 172.10 kJ mol−1 and pre-exponential factor (A) was 1.22E + 17, 5.04E + 10 and 1.80E + 15 min−1, respectively, while the optimal mechanism function was G(α) = [1 − (1 − α)1/3]2(n = 2). The calculated thermodynamic parameters included ΔH (163.77–166.90 kJ mol−1), ΔS (− 62.25–61.28 J mol−1 K−1) and ΔG (145.41–184.02 kJ mol−1). The Py-GC/MS results showed mainly produced nitrogen-containing compounds, acidic alcohol compounds, aldehydes, ketones, esters, benzenes and hydrocarbons. This study highlights KWFR can be considered as an attractive feedstock for bioenergy and bio-based chemicals and meanwhile may help to solve the problem of kitchen wastes digestion tailings. [ABSTRACT FROM AUTHOR]

Soil microbial use efficiency of straw carbon (C), which is the proportion of straw-C microbes assimilate into new biosynthetic material relative to C lost out of the system as CO2, is critical in increasing soil organic C (SOC) content, and hence maintaining soil fertility and productivity. However, the effect of chemical structures of the organic amendments (OAs) on the microbial use efficiency of straw-C remains unclear. The effect of the chemical structure of the OAs on microbial use efficiency of straw-C was elucidated by a combination of 13C-straw labeling with high-throughput sequencing and pyrolysis-GC/MS. We found a strong positive correlation between the microbial use efficiency of straw-C and the proportion of heterocyclic compounds (Hete_C). The microbial use efficiency of straw-C was highest in soil supplemented with Hete&lowbar;C-dominant OAs, which significantly shifted microbial community structure toward fungal dominance. Specifically, fungal-to-bacterial ratio, fungal richness, and the relative abundance of Ascomycota were higher in soil with a higher proportion of Hete&lowbar;C-dominant OAs. Together, our study suggests that OAs with high proportion of Hete&lowbar;C promote the microbial use efficiency of straw-C by increasing the dominance of fungi in the soil microbial community in agroecosystems. [ABSTRACT FROM AUTHOR]

Thermal characterization of kraft lignin (KL) prepared from mixed hardwoods was conducted to determine their thermal and thermooxidative stability, glass transition temperature (Tg), pyrolysis products composition, and syringyl/guaiacyl ratio. Two milled wood lignins (MWLs) from acacia (MWL-aca) and mixed hardwoods (MWL-mhw), the same hardwood species employed in the production of KL, were also characterized for comparison with KL. Thermogravimetric analysis (TGA) indicated that KL had higher thermal and thermo-oxidative stability than MWLs. Based on differential scanning calorimetry (DSC), the Tg of KL was 63.2 °C, while MWLs gave similar values near 165 °C. The syringyl (S), guaiacyl (G), p-hydroxyphenyl (H) composition of KL acquired from pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) at 675 °C was 48:44:8 (S/G ratio 1.07), while MWL-aca and MWL-mhw were 31:60:9 and 46:48:6, respectively. [ABSTRACT FROM AUTHOR]

Tire and road wear particles (TRWP) are generated at the frictional interface between tires and the road surface. This mixture of tire tread and road pavement materials can migrate from roads into nearby water bodies during precipitation events. The absence of mass-based measurements in marine environments introduces uncertainty in environmental risk assessments and fate and transport models. Surface water and sediment samples were collected from nine Osaka Bay (Japan) locations for TRWP mass determination in June 2023. Additionally, sediment traps were deployed for approximately nine weeks at three locations near the mouth of the Yodo River. Large volumes of surface water (approximately 10,000 L/sample) were sequentially filtered (100, 10, 0.5 μm) to capture retained solids between 0.5 μm and 5 mm. Sediment and retained solids were analyzed for TRWP using Pyrolysis-Gas Chromatography/Mass Spectrometry (Py-GC/MS) and the particulate zinc (Zn) method. TRWP concentrations in surface water retained solids and sediment showed spatial variation, with median concentrations of 231 μg/g dw and 312 μg/g (grab samples) and 460 μg/g (trap samples), respectively, with higher concentrations near the mouth of the Yodo River, indicating greater influence from urban areas. The study's findings improve understanding of the Py-GC/MS method, highlighting the necessary adjustments to reduce biases and enhance accuracy, as well as the relationship between Py-GC/MS and the particulate Zn method. These results can inform future environmental risk assessments, fate and transport models, and strategies for mitigating TRWP in marine environments., Competing Interests: Declaration of competing interest The authors disclose the following financial interests and personal relationships that may be viewed as potential conflicts of interest: the authors are or have been employed by consulting firms that provide scientific advice to government agencies, corporations, law firms, and various scientific and professional organizations. This work was funded by the Tire Industry Project (TIP), a global, voluntary initiative led by CEOs from 10 major tire companies, operating under the World Business Council for Sustainable Development (WBCSD). TIP's goal is to proactively identify and address the potential human health and environmental impacts of tires in support of a more sustainable future. The authors were engaged as consultants by TIP, while contract laboratories were hired to conduct the analytical analyses. The study's design, execution, interpretation, and manuscript preparation were carried out exclusively by the authors., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Plastic particles are ubiquitous pollutants in the living environment and food chain but no study to date has reported on the internal exposure of plastic particles in human blood. This study’s goal was to develop a robust and sensitive sampling and analytical method with double shot pyrolysis - gas chromatography/mass spectrometry and apply it to measure plastic particles ≥700 nm in human whole blood from 22 healthy volunteers. Four high production volume polymers applied in plastic were identified and quantified for the first time in blood. Polyethylene terephthalate, polyethylene and polymers of styrene (a sum parameter of polystyrene, expanded polystyrene, acetonitrile butadiene styrene etc.) were the most widely encountered, followed by poly(methyl methacrylate). Polypropylene was analysed but values were under the limits of quantification. In this study of a small set of donors, the mean of the sum quantifiable concentration of plastic particles in blood was 1.6 µg/ml, showing a first measurement of the mass concentration of the polymeric component of plastic in human blood. This pioneering human biomonitoring study demonstrated that plastic particles are bioavailable for uptake into the human bloodstream. An understanding of the exposure of these substances in humans and the associated hazard of such exposure is needed to determine whether or not plastic particle exposure is a public health risk.

The photodegradation of macroplastics in the marine environment remains poorly understood. Here, we investigated the weathering of commercially available plastics (tabs 1.3 × 4.4 × 0.16 cm), including high-density polyethylene, low-density polyethylene, polypropylene, polystyrene, and polycarbonate, in seawater under laboratory-simulated ultraviolet A radiation for 3-9 months, equivalent to 25-75 years of natural sunlight exposure without considering other confounding factors. After the exposure, the physical integrity and thermal stability of the tabs remained relatively intact, suggesting that the bulk polymer chains were not severely altered despite strong irradiation, likely due to their low specific surface area. In contrast, the surface layer (∼1 μm) of the tabs was highly oxidized and eroded after 9 months of accelerated weathering. Several antioxidant additives were identified in the plastics through low temperature pyrolysis coupled with gas chromatography/mass spectrometry (Pyr-GC/MS) analysis. The Pyr-GC/MS results also revealed many new oxygen-containing compounds formed during photodegradation, and these compounds indicated the dominance of chain scission reactions during weathering. These findings highlight the strong resistance of industrial macroplastics to weathering, emphasizing the need for a broader range of plastics with varying properties and sizes to accurately estimate plastic degradation in the marine environment.

Background: The Arctic permafrost stores enormous amount of carbon (C), about one third of global C stocks. However, drastically increasing temperature in the Arctic makes the stable frozen C stock vulnerable to microbial decomposition. The released carbon dioxide from permafrost can cause accelerating C feedback to the atmosphere. Soil organic matter (SOM) composition would be the basic information to project the trajectory of C under rapidly changing climate. However, not many studies on SOM characterization have been done compared to quantification of SOM stocks. Thus, the purpose of our study is to determine soil properties and molecular compositions of SOM in four different Arctic regions. We collected soils in different soil layers from 1) Cambridge Bay, Canada, 2) Council, Alaska, USA, 3) Svalbard, Norway, and 4) Zackenberg, Greenland. The basic soil properties were measured, and the molecular composition of SOM was analyzed through pyrolysis-gas chromatography/mass spectrometry (py-GC/MS). Results: The Oi layer of soil in Council, Alaska showed the lowest soil pH and the highest electrical conductivity (EC) and SOM content. All soils in each site showed increasing pH and decreasing SOC and EC values with soil depth. Since the Council site was moist acidic tundra compared to other three dry tundra sites, soil properties were distinct from the others: high SOM and EC, and low pH. Through the py-GC/MS analysis, a total of 117 pyrolysis products were detected from 32 soil samples of four different Arctic soils. The first two-axis of the PCA explained 38% of sample variation. While short- and mid-hydrocarbons were associated with mineral layers, lignins and polysaccharides were linked to organic layers of Alaska and Cambridge Bay soil. Conclusions: We conclude that the py-GC/MS results separated soil samples mainly based on the origin of SOM (plants- or microbially-derived). This molecular characteristics of SOM can play a role of controlling SOM degradation to warming. Thus, it should be further investigated how the SOM molecular characteristics have impacts on SOM dynamics through additional laboratory incubation studies and microbial decomposition measurements in the field. [ABSTRACT FROM AUTHOR]

Here, we report an analysis method for determining PHA (polyhydroxyalkanoates) contents and their monomer composition in microbial cells based on pyrolysis gas chromatography combined with mass spectrometry (Py-GC/MS). Various kinds of microbial cells accumulating different PHA contents and monomer compositions were prepared through the cultivation of Ralstonia eutropha and recombinant Escherichia coli. Py-GC/MS could analyse these samples in a short time without complicated pretreatment steps. Characteristic peaks such as 2-butenoic acid, 2-pentenoic acid, and hexadecanoic acid regarding PHA compositions and cell components were identified. Considering constituents of cells and ratios of peak areas of dehydrated monomers to hexadecanoic acid, a simple equation for estimation of PHA contents in microbial cells was derived. Also, monomer compositions of poly(3-hydroxybutyrate- co -3-hydroxyvalerate) (PHBV) in R. eutropha could be successfully determined based on peak area of 2-butenoic acid and 2-pentenoic acid of Py-GC/MS, which are the corresponding species of 3-hydroxybutyrate (3HB) and 3-hydroxyvalerate (3HV) in PHBV. Correlation of results between GC-FID and Py-GC/MS could be fitted very well. This method shows similar results for the samples obtained from same experimental conditions, allowing rapid and reliable analysis. Py-GC/MS can be a promising tool to rapidly screen PHA-positive strains based on polymer contents along with monomer compositions. [ABSTRACT FROM AUTHOR]

Intact peatlands serve as a globally important carbon sink. However, impacts from climate change, extraction, and drainage increase aerobic decomposition in these ecosystems-shifting their carbon flux from sink to source. A variety of projects are ongoing to restore peatlands to their natural or near-natural states; however, for carbon sequestration, net accumulation of peat relative to decomposition is of primary importance. Molecular analysis techniques provide information on peat growth and degradation trends dating from centuries to millennia. Pyrolysis coupled to gas chromatography mass spectrometry (Py-GC/MS) has been proposed for the rapid characterization of molecular biomarkers in organic matter. This paper reviews plant and microbial biomarkers analyzable via Py-GC/MS for peatland ecosystems, associated challenges, and future applications of the technique. It is noted that far fewer organism-specific biomarkers have been identified via Py-GC/MS for microbial communities in comparison to plant-based studies, and as a topic remains an area greatly needing additional research. In the future, through improved Py-GC/MS-derived fingerprinting of peatland molecular components, periods of degradation and growth could be more precisely distinguished and described, even in profiles where changes in contributing source material are not macroscopically visible. [ABSTRACT FROM AUTHOR]

Chlorophyll is frequently used as a proxy for autochthonous production in lakes. This use of chlorophyll concentrations in sediments to infer historical changes in lake primary production relies heavily on the assumption that preservation is sufficient to reflect the productivity in a meaningful way. In this study, we use a series of freeze cores from a lake with annually laminated sediments to assess how reliable down-core trends in chlorophyll are, and to what extent chlorophyll is degraded in the sediment. A striking consistency in the down-core chlorophyll trends in four sediment cores collected in different years (1983, 1992, 2002 and 2010) shows that the sediment preserves a consistent chlorophyll signal over longer timescales. However, there are also clear signs that diagenetic processes within the sediment affect the chlorophyll concentration in sediment layers younger than 10–15 years. This implies that care is needed when interpreting chlorophyll trends in recent sediments. Further, our data show that high-performance liquid chromatography (HPLC) and visible reflectance spectroscopy (VRS) detect similar chlorophyll concentrations for recently dried samples. A third analytical technique, pyrolysis–gas chromatography/mass spectrometry, which provides semi-quantitative values for chlorophyll, also produce a temporal trend that is highly correlated with data from the two quantitative techniques. For samples that have been stored dried at room temperature for several years there is, however, a large discrepancy between the two quantitative techniques. The VRS method is more robust with regards to degradation during storage, while HPLC results demonstrate clear storage effects. [ABSTRACT FROM AUTHOR]

Focusing on the relatively unexplored presence of micro- and nano-plastic aerosol particles, this study quantitatively assessed the emission of nano-plastic particles during the machining of carbon fiber reinforced plastic (CFRP) in the working environment. Measurements of aerosol particles smaller than 1 µm in size were performed by aerosol mass spectrometry. The findings revealed that concentrations of carbonous aerosol particles (organic aerosol and refractory black carbon (rBC)) were higher during working hours than during non-working hours. Positive matrix factorization identified CFRP particles as a significant source, contributing an average of approximately 30% of concentration of carbonous aerosol particles during working hours. This source apportionment was corroborated by the presence of bisphenol A and F fragments, principal components of the epoxy resins used in CFRP, and was corroborated by similarities to the carbon cluster ion distribution observed in rBC during CFRP pipe-cutting operations. Further, the particle size distribution suggested the existence of plastic aerosol particles smaller than 100 nm. This study established the method to quantitatively distinguish nano-plastic aerosol particles from other aerosol particles in high temporal resolution and these techniques are useful for accurately assessing exposure to nano-plastic aerosol particles in working environments. [Display omitted] • Aerosol particles from machining of carbon fiber reinforced plastic were assessed. • The positive matrix factorization method distinguished plastic particles. • We found plastic aerosol particles smaller than 100 nm in working environment. • Our method enables precise exposure assessment of nano-plastic particle. [ABSTRACT FROM AUTHOR]

Nanoplastics, owing to their small particle size, pose a significant threat to creatures, deserving heightened attention. Numerous studies have investigated microplastics pollution and their removal efficiency in drinking water treatment plants, none of which have involved nanoplastics due to lacking a suitable analytical method. This study introduced a feasible method of combing AFM-IR and Pyr-GC/MS to identify and quantify nanoplastics (20–1000 nm) for a preliminary understanding of their fate during drinking water treatment processes. Resolving of chemical functional groups and pyrolysis products from AFM-IR and Pyr-GC/MS data demonstrated the presence of PE and PVC nanoplastics in this drinking water treatment plant. The initial influent abundances of PE and PVC nanoplastics were 0.86 μg/L and 137.31 μg/L, with subsequent increase to 4.49 μg/L and 208.64 μg/L in ozonation contact tank unit. Then a gradual decreasing was observed along water process, achieving 98.4% removal of PE nanoplastics and 44.0% removal of PVC nanoplastics, respectively. Although this drinking water treatment plant has exhibited a certain level of nanoplastics removal efficiency, particular attention should be directed to the oxidation unit, which appears to be a significant source of nanoplastics. This study will lay a foundation for revealing nanoplastics pollution in the environment. [Display omitted] • A combined method of AFM-IR and pyr-GC/MS was proposed for nanoplastics analysis. • Both PE and PVC nanoplastics were identified in this drinking water plant. • The drinking water plant can remove nanoplastics to some extent. • Ozonation unit serves as source of nanoplastics in drinking water plant. [ABSTRACT FROM AUTHOR]

BACKGROUND White rot fungi have been used to improve the nutritive value of lignocellulose for ruminants. In feed analysis, the Van Soest method is widely used to determine the cell wall contents. To assess the reliability of this method (Method A) for determination of cell wall contents in fungal‐treated wheat straw, we compared a combined monosaccharide analysis and pyrolysis coupled to gas chromatography with mass spectrometry (Py‐GC/MS) (Method B). Ruminal digestibility, measured as in vitro gas production (IVGP), was subsequently used to examine which method explains best the effect of fungal pretreatment on the digestibility of wheat straw. RESULTS: Both methods differed considerably in the mass recoveries of the individual cell wall components, which changed on how we assess their degradation characteristics. For example, Method B gave a higher degradation of lignin (61.9%), as compared to Method A (33.2%). Method A, however, showed a better correlation of IVGP with the ratio of lignin to total structural carbohydrates, as compared to Method B (Pearson's r of −0.84 versus −0.69). Nevertheless, Method B provides a more accurate quantification of lignin, reflecting its actual modification and degradation. With the information on the lignin structural features, Method B presents a substantial advantage in understanding the underlying mechanisms of lignin breakdown. Both methods, however, could not accurately quantify the cellulose contents – among others, due to interference of fungal biomass. CONCLUSION: Method A only accounts for the recalcitrant residue and therefore is more suitable for evaluating ruminal digestibility. Method B allows a more accurate quantification of cell wall, required to understand and better explains the actual modification of the cell wall. The suitability of both methods, therefore, depends on their intended purposes. © 2019 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Plastic pollution is a significant environmental concern because microplastics (MPs) accumulate in various ecosystems; therefore, the accurate identification and quantification of MPs in environmental samples is crucial. This study presents a new sequential analytical method that combines Fourier-transform infrared spectroscopy (FTIR) and pyrolysis-gas chromatography/mass spectrometry (Pyr-GC/MS) to characterize and quantify MPs. FTIR with a microscope allows the identification of the polymer type and physical dimensions of MPs, whereas Pyr-GC/MS enables determining the chemical composition of MPs with plastic additives. Pretreated wastewater influent samples spiked with reference MPs were filtered through an Al 2 O 3 disk for FTIR analysis, and the surface contents were collected and subjected to Pyr-GC/MS analysis. The mass of the reference MPs estimated using FTIR were in good agreement but were slightly lower than those obtained using Pyr-GC/MS. This finding supports the notion that the proposed sequential method can be used to determine both the number and the mass of MPs in environmental samples. [Display omitted] • A sequential analytical method using FTIR and Pyr-GC/MS was proposed. • The method was able to provide both the number and the mass of MPs in a sample. • Masses of MPs estimated using FTIR agreed well with those using Pyr-GC/MS. • Slightly greater mass obtained using Pyr-GC/MS is likely via contribution of smaller MPs. [ABSTRACT FROM AUTHOR]

Lignin is a group of cell wall localised heterophenolic polymers varying in the chemistry of the aromatic and aliphatic parts of its units. The lignin residues common to all vascular plants have an aromatic ring with one para hydroxy group and one meta methoxy group, also called guaiacyl (G). The terminal function of the aliphatic part of these G units, however, varies from alcohols, which are generally abundant, to aldehydes, which represent a smaller proportion of lignin monomers. The proportions of aldehyde to alcohol G units in lignin are, nevertheless, precisely controlled to respond to environmental and development cues. These G aldehyde to alcohol unit proportions differ between each cell wall layer of each cell type to fine-tune the cell wall biomechanical and physico-chemical properties. To precisely determine changes in lignin composition, we, herein, describe the various methods to detect and quantify the levels and positions of G aldehyde units, also called coniferaldehyde residues, of lignin polymers in ground plant samples as well as in situ in histological cross-sections., (© 2024. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)

Graphical abstract Abstract The Cuban-American artist Carmen Herrera (born 1915) was the subject of a partial retrospective, titled Carmen Herrera: Lines of Sight , held at the Whitney Museum of American Art, New York, in the fall of 2016. On this occasion, it was noted that the artist had listed the binding media for all the paintings in the exhibit as acrylic even though the earliest works date from the late 1940s to early 1950s, when Herrera was in Paris and acrylics were not yet known to be commercially available in Europe. Questioned about the unexpected media assignments, Herrera recalled buying early acrylic paints in an art supply store near her studio in the French capital. Thus, for this study, a selection of five paintings by Carmen Herrera dated from 1948 to 1952, for which there was no sign or record of previous conservation treatments, were analyzed with a variety of non-invasive and micro-invasive instrumental techniques to characterize the painting materials in order to ascertain whether early experimental acrylic formulations might have been used. A preliminary investigation of the elemental composition of the paints entailed non-invasive analysis of the artworks with X-ray fluorescence spectroscopy. Twenty-one paint samples were then removed from selected areas for micro-invasive examination. Fourier-transform infrared spectroscopy and pyrolysis–gas chromatography/mass spectrometry with and without sample derivatization with tetramethyl ammonium hydroxide were employed to gather detailed information on the chemical composition of the binding media. In addition, complementary analyses by Raman spectroscopy and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy were conducted to shed light on the pigments, colorants, and extenders present. Results revealed that the paints are composed of a range of both traditional and modern materials, including: calcite, gypsum, barite, and titanium white (in the form of rutile and anatase); cadmium yellows, oranges, and reds; Pigment Red 83 – the synthetic counterpart of natural dye alizarin (1,2-dihydroxyanthraquinone) – precipitated onto an aluminum-rich substrate; viridian and emerald green; cerulean blue, cobalt blue, as well as Prussian blue; iron-containing earths and umber-based pigments; as well as bone and/or ivory black. More remarkably, a complex progression of organic binders was uncovered: mixtures of modified oils, detected in paintings dated to 1948 and 1949, were gradually replaced or combined with other binding media, such as acrylics (mostly n -butyl methacrylate), polyvinyl acetate, and oil-based alkyds based on ortho -phthalic acid, in works painted during the following three years. Remarkably, the first occurrence of acrylic binders was observed in a painting dated to 1949, well before the date of introduction to the European market of the first acrylic-based paints by George Rowney & Sons in 1963. In addition to offering insight into Herrera's materials and techniques, this study represents a major advancement in the current scholarship regarding the availability and use of acrylic-based artists' paints in Europe. [ABSTRACT FROM AUTHOR]

The phenolic hydroxyl group (Phe-OH), a representative functional group in the lignin macromolecule, was found to play an important role in lignin pyrolysis in the presence of zeolite catalyst. We prepared lignin samples with different Phe-OH content by chemoselectivity controlled stepwise methylation. These methylated lignins had almost the same structures as the original lignin except for their Phe-OH content. However, the instantaneous decomposition rate of methylated lignins by exposure to heat increased with increasing degree of methylation due to restriction of intermolecular hydrogen bonding of the Phe-OH. It suggested that Phe-OH content changed the thermal decomposition behavior of lignin. Upon pyrolysis in the absence of catalyst, methoxylated aromatics compounds such as p -methy-, p -ethyl-, and p -vinylanisole (evidence of methylation) were released from methylated lignins. Pyrolyzing methylated lignins with zeolite Y catalyst produced benzene, toluene, xylenes, and naphthalenes as main aromatic hydrocarbons, and their yields showed. A positive correlation with the degree of methylation. In addition, oxygenated functional groups in pyrolysis products were completely decomposed with zeolite Y catalyst. We obtained 39% enhanced aromatic hydrocarbons yield in totally methylated lignin compared with the original lignin. In this study, we propose plausible pathways for methylated lignin pyrolysis over zeolite Y on the basis of our observations. [ABSTRACT FROM AUTHOR]

In podzols important environmental issues converge, including dissolved organic matter (DOM) transport, DOM-metal binding, and carbon storage in the subsoil. Therefore, it is important to understand the formation and degradation of podzols in relation to (changes in) environmental conditions. For this purpose a Holocene barrier island with coastal sand dunes (Ilha Comprida, SE Brazil) was chosen as study area. The island is build-up of five geomorphic units that have different age (from >5000 to 325 y BP), vegetation ( restinga ecosystems), soil hydrology (flat units or units with ridges and swales) and drainage (poorly drained, well-drained, and improved drainage). Representative profiles were studied for each geomorphic unit, resulting in 100 samples from A, E, B, and C horizons, from which soil organic matter (SOM) was isolated by alkaline extraction. To better understand carbon sources and dynamics, we additionally sampled litter from different vegetation types and DOM from various sources. The molecular composition of SOM, DOM and litter was analyzed with pyrolysis gas chromatography mass spectrometry (pyrolysis-GC/MS). Comparing the pyrolysates of all samples (DOM, SOM and litter) factor analysis demonstrated that the major difference in molecular composition (factor 1) was related to the contribution from DOM (phenol, acetic acid, benzofurans, pyridine, benzene and naphthalene) or in-situ root material (straight chain aliphatics and methoxyphenols from the biomacromolecules suberan and lignin, respectively). The contribution from DOM or roots was characteristic for a profile i.e. without much change with depth. Factor 2 reflected decomposition processes, and showed that the predominantly DOM-derived B horizons were relatively enriched in aromatics compared to DOM, indicating selective decay and/or selective precipitation. In geomorphic units with swales and ridges that received DOM via groundwater flow from the catchment area, the B horizon was predominantly DOM-derived; these profiles showed large differences in the contribution from black carbon (BC; (poly)aromatics), with the younger profiles showing a larger contribution from BC in precipitated DOM. B horizons with a relatively large contribution from in-situ root materials were found in well-drained soils and in some of the poorly drained soils without lateral groundwater flow from the catchment area, i.e., the flat geomorphic unit without ridges and swales. Microbial material (N-containing compounds and sugars) was associated with relatively recent SOM and with well-drained conditions at present. i.e., well-drained profiles, and profiles with improved drainage. [ABSTRACT FROM AUTHOR]

Highlights • Beechwood xylan includes one uronic acid moiety per 7.7 xylan units. • Two DTG peaks are observed for xylan, while only one for demineralized xylan. • The sodium salt of uronic acid degrades at the lower DTG temperature. • Some xylose units degrade along with the sodium salt of uronic acid. • Pyrolysis products are different for original and demineralized xylans. Abstract The 4- O -methyl- D -glucuronic acid groups attached to xylose chains in wood xylan can form uronate salts with alkali and alkaline earth metal cations. These uronic acid and metal uronate moieties may act as acid and base catalysts, respectively, during xylan pyrolysis. In this study, commercial beechwood xylan (in which most uronic acids were present as sodium salts) and a demineralized version of the same material containing free uronic acid groups were pyrolyzed at 220–340 °C under N 2 and the decomposition behaviors of the uronic acid and xylose units were determined. In the case of the original xylan, differential thermogravimetric (DTG) peaks were assigned to the degradation of sodium uronate and some xylose units (at lower temperatures) and to the decomposition of the remaining xylose units (at higher temperatures). In contrast, the demineralized xylan generated only one DTG peak in the intermediate temperature range, corresponding to the simultaneous decomposition of both uronic acid and xylose units. Thus, the effect of sodium uronate on the pyrolysis of the original xylan was only regional, whereas the free uronic acid affected the demineralized xylan in a more homogeneous manner. Additional data from pyrolysis-gas chromatography-mass spectrometry revealed that the compositions of the pyrolysis products were also different for these two xylan samples. The results of this work provide an improved understanding of wood pyrolysis mechanisms. [ABSTRACT FROM AUTHOR]

Lignin was isolated through mild acidolysis from local wood sources such as beech wood and chestnut wood sawdust, a high-volume side product of wood industries. The lignin fractions were characterized by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), Fourier-transform infrared (FTIR), ultraviolet-visible (UV-Vis) and two-dimensional heteronuclear single-quantum correlation nuclear magnetic resonance (2D HSQC NMR) spectroscopies and size exclusion chromatography (SEC). The Klason lignin (KL) content and polysaccharide composition were determined using traditional methods. Lignin nanoparticles (LNPs) were prepared via a non-solvent method involving dialysis and characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) and FTIR and UV-VIS spectroscopies. Semi-porous as well as hollow nanoparticles endowed with a spherical shape were observed. The large majority of the LNPs exhibited an average particle diameter of 90–120 nm. Dynamic light scattering (DLS) analysis showed that both distribution and frequency of dimensional classes of LNPs are clearly affected by the lignin solvent system, i.e. solvent selection governs the size distribution of LNPs. [ABSTRACT FROM AUTHOR]

Knowledge of the molecular composition of soil organic matter (OM) and the interaction of OM with soil minerals is needed to fundamentally understand how the persistence of OM is affected by land use. We investigated organic carbon (C) fractions, content of short-range order constituents (SRO) (i.e., Al and Fe oxy-hydroxides) and OM chemistry of 45 top soils across a range of soil orders and land uses in New Zealand. The objective of the study was to assess the influence of different land uses on the OM quality and quantity of soils that differed in their content of SRO constituents. The C fractions considered were cold + hot water-soluble C (C H2O ), C recovered in the residuum after HF treatment (C HF-residuum ), and C not so recovered (C HF-mobile ). Carbon in particulate OM (C POM ) was determined in non-Allophanic soils, and C extractable with sodium pyrophosphate (C p ) in Allophanic soils. The chemistry of the HF-residual OM was investigated using pyrolysis-GC/MS. The highest C content was found under grazed grasslands and, among soil orders, in Allophanic soils, which had the largest C HF-mobile and C HF-residuum contents. Yet compared to non-Allophanic, Allophanic soils were more vulnerable to loss of C (C HF-mobile and C HF-residuum ) when used for cropping. The relative contribution of microbial- vs. plant-derived OM was influenced by soil order and land use: microbial-derived OM increased as the presence of SRO constituents increased, these being more abundant in Allophanic soils; soils under ungrazed grasslands had the largest contribution of fresh plant-derived molecules to OM (and of C HF-residuum to total C) while cropping had a negative impact on the contribution of plant-derived OM, consistent with a decrease in C POM . Overall, the results showed that not only is the ability of New Zealand soils to store C soil-specific, but so too is their vulnerability to losing it when under specific land use. [ABSTRACT FROM AUTHOR]

Highlights • Molecular composition of solid-state anaerobic digestates of pig slurry and straw studied by Py-GC/MS. • Highest OM loss found when using 2 and 4 percolate recirculation per day. • Greater polysaccharides consumption found when increasing recirculation frequency. • Enrichment in Lig-compounds found when increasing recirculation frequency. • Positive effect of percolate recirculation on OM degradation and stabilization. Abstract Straw and pig slurry Solid-State Anaerobic Digestion (SS-AD) was carried out in a pilot-scale apparatus using percolate recirculation technology. The digestion experiments were performed using 1, 2 and 4 recirculations per day; an additional experiment without percolate recirculation was used as control. The initial mixture and the digestates were analysed by means of chemical analyses and Pyrolysis–Gas Chromatography/Mass Spectrometry (Py–GC/MS), a direct analytical technique that allows investigating the changes in the organic matter (OM) composition of digestates and the effect of percolate recirculation frequency. Chemical analyses suggested a positive effect of percolate recirculation on OM degradation. The highest values of OM loss were found with 2 (26%) and 4 (31%) recirculation cycles per day, that also corresponded with the lowest values of the hydrophilic water extractable organic matter fraction (5.5 and 6.3% respectively). Py-GC/MS showed that the anaerobic digestion proceeded with progressive polysaccharide degradation (from c. 19% in the initial mixture to 10–8% with 2–4 recirculation cycles) and selective enrichment of lignin derived compounds (from c. 58% in the initial mixture to 67–69% with 2–4 recirculation cycles). In addition, a shift in the fatty acids distribution was observed with a decrease in the long/short chain ratio of fatty acid methyl esters. These results indicate that under our experimental conditions, percolate recirculation had a positive effect on the OM degradation. Also OM stabilization is observed with relative increases in recalcitrant lignin at the expense of the more liable polysaccharide fraction. This paper represents the first attempt to apply Py-GC/MS to evaluate the OM quality in digestates obtained by SS-AD of pig slurry and straw optimized by percolate recirculation. [ABSTRACT FROM AUTHOR]

Combustion of undesirable components with a high calorific value (waste: plastics, rubber, chipboard, plywood etc.) contribute to an increased emissions of PM particles. The possibility of identification of non-desirable fuels was verified by analysis of unburned carbon from bottom ash by means of pyrolysis-GC/MS. Compounds derived from thermal conversion of main wood components in the unburned carbon are formed by aldehydes, ketones, alkanes, alkenes, alkanoates, polycyclic aromatic hydrocarbons, compounds containing benzene, compounds containing phenol and nitrogen. Unburned carbon from plywood/chipboard contains compounds with nitrogen (heterocyclic and aliphatic) in increased concentrations (33–51 ng/mg) compared with unburned carbon from pure wood (7–12 ng/mg). The concentrations increased almost two times were proved for compounds containing phenols in unburned carbon from wood composite. Total amount of determined organic compounds is also almost two times higher than that contained in unburned carbon from wood. The indication of waste wood combustion from unburned carbon is possible using the ratio: phenol/(2-methylphenol+4-methylphenol). [ABSTRACT FROM AUTHOR]

The formation of sombric horizons (dark horizons in the subsoil) is still not understood. In order to improve our understanding of the formation of sombric horizons we studied these soils in southern Brazil from various perspectives. The lateral configuration and grain size distribution excluded the possibility that the sombric horizon is a paleosol covered by an eolian deposit or colluvium. Micromorphology showed intense biological activity, indicating strong bioturbation. The absence of clay and OM coatings indicates that the sombric horizon in the study area was not formed by illuviation. Considering changes with depth, phytoliths and δ 13 C isotopes clearly showed that the OM from the sombric horizon had a larger contribution from grasses, while a larger contribution from black carbon (BC) was evidenced by the molecular composition. A larger contribution from grasses and BC both correspond to drier climatic conditions. However, similar depth trends for δ 13 C and PAHs were found in the reference profile (without sombric horizon), in agreement with climatic change but not explaining the different morphology. The molecular composition and C/N ratio showed that the profiles differed in degree of decomposition, with the OM in the soils that contained a sombric horizon being more decomposed than that in the reference profile. The sombric horizon is thus a remnant of an earlier phase of soil formation under a drier climate, which is made visible by differences in decomposition of OM related to subsequent more humid conditions. Stronger decomposition in the profiles with a sombric horizon may be related to better drainage, explaining their occurrence in the highest positions within the landscape and suggesting a topographic control. [ABSTRACT FROM AUTHOR]

Important parameters that influence biochar properties include charring temperature and biomass type. We characterized the molecular properties of biochars from five agricultural residues with pyrolysis gas chromatography mass/spectrometry (pyrolysis-GC/MS) in comparison with atomic H/C and N/C ratios. Feedstocks included chicken manure, eucalyptus sawdust, coffee husk, sugarcane bagasse and pine bark. Biochars produced at three different temperatures (T char ) were analyzed, including 350, 450 and 750 °C, as well as the uncharred materials. The optimum temperature during analysis with pyrolysis-GC/MS (T py ) was examined. T py 600 °C gave the best results for all T char by showing a larger diversity of pyrolysis products compared to T py 700 °C and 800 °C; T py 600 °C was therefore used for qualitative and quantitative comparison of the samples. Charring temperature was the dominant factor that determined the chemical composition of the biochar pyrolysates. Uncharred feedstocks had the largest contribution from carbohydrates, lignin phenols and long chain n -alkanes, all of which rapidly decreased with charring; biochars produced at T char 350 and 450 °C showed the largest contribution from phenols, mid-chain n -alkanes, benzofurans, indenes, biphenyls and PAHs, from which the benzofurans, indenes, biphenyls and PAHs were particular abundant in samples produced at T char 450 °C; pyrolysates of biochars produced at T char 750 °C were characterized by branched aliphatics, short chain n -alkanes/ n -alkenes and low molecular weight (LMW) benzenes. Factor analysis showed that the variation of products differed largely within some chemical groups. For the N-containing compounds, caffeine, C 16 alkylnitrile and diketopiperazines were associated with uncharred materials, benzonitriles and quinolines were associated with T char 350–450 °C. Another part of the variation of N-containing compounds was associated with chicken manure, and to a lesser extend also coffee husk, independently of T char . For all five agricultural residues, the highest chemical diversity was found for biochar produced at T char 350 °C. As the charring temperature increased, the diversity of pyrolysis products diminished. [ABSTRACT FROM AUTHOR]

Acrylic pressure-sensitive adhesives (APSAs) have been used in a variety of fields and the composition of their monomers is a very important factor in determining their physical properties. Monomers containing polar functional groups, such as acrylic acid (AA), are often used as raw materials for APSAs, and the number of these monomer units in the polymer chain has a significant effect on the adhesive properties. However, due to its high reactivity and polarity, it is not easy to accurately quantify AA in APSAs by conventional reactive pyrolysis gas chromatography mass spectrometry (Py-GC/MS). In this study, quantitative analysis of AA in APSAs was examined by reactive Py-GC/MS using N,O -bis(trimethylsilyl)trifluoroacetamide (BSTFA) as a trimethylsilylation (TMS) reagent (Py (BSTFA)-GC/MS). First, the APSA sample was mixed with BSTFA and heated at 60 ºC for 30 min to accelerate TMS derivatization of any unpolymerized AA monomers (AA-TMS). If unreacted BSTFA remains after derivatization, it will react with AAs produced by the pyrolysis of acrylic ester units. These additional AA monomers,will results in the over-estimation of the true amount of unpolymerized AA monomers. To prevent this undesirable effect by residual reagent, the TMS-derivatized sample was further heated at 100 ºC for 10 min before pyrolysis in order to remove residual BSTFA and solvent. The derivatized sample was measured by Py-GC/MS at 600 ºC and the relative standard deviation of the peak area ratio of AA-TMS derived from unpolymerized AA monomers to the internal standard (anthracene-d 10) was less than 5% (n = 5). In the calibration curves made for four APSA samples with known compositions, good linearity was obtained for the raw materials of butyl acrylate and 2-ethylhexyl acrylate in addition to AA-TMS. Quantitative analysis of AA monomers in a commercial APSA sample showed fairly good agreement with the amount of AA determined by the official method of analysis using the acid-base titration (JIS K 5601–2–1). The results obtained in this study indicate that Py (BSTFA)-GC/MS is effective for the compositional analysis of APSAs. • Acrylic acid in acrylic pressure-sensitive adhesives was determined by Py-GC/MS. • N,O -bis(trimethylsilyl)trifluoroacetamide was used as trimethylsilylation reagent. • Two step heating was adopted to accelerate derivatization reaction. • Excess reagent was also removed by two step heating to obtain quantitative analysis. [ABSTRACT FROM AUTHOR]

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Corona activity on the surface of silicone rubber has high impact on variation in hydrophobicity of the material, and on corona inception voltage (CIV) of water droplet sitting on the corona degraded surface. The CIV is high under negative DC as compared to positive DC/AC voltages. Increase in conductivity of water droplet reduces CIV. Surface charge accumulation studies indicate that the charge retention capability of the insulating material gets reduced drastically with silicone rubber damaged due to corona causing degradation of surface. Irrespective of the number of cycles of corona discharge activities carried out, the time constant of charge decay, after the removal of charge injection, remains the same. The water droplet initiated discharges under AC and DC voltages radiate UHF signal in the bandwidth 0.3?1.2 GHz. With single droplet sitting on top of the corona damaged silicone rubber, the amount of charge retained by the water droplet is low when the droplet is placed and charged immediately after corona discharge activity to surface of the insulating material. When the water droplet is placed after a certain time period, the charge accumulation characteristics of silicone rubber are regained. Leakage current measured during water droplet discharge studies through recurrent plot (RP) analysis reveals that, under AC voltage, it is possible to classify corona inception, arcing and bridging of water droplet between high voltage and ground electrode. The RP obtained for the current signals generated due to water droplet discharges under positive and negative DC voltages are different. The amount of damage caused to silicone rubber due to water droplet is high under negative DC voltage as compared to positive/AC voltages. While correlating the level of damage to the insulating material due to water droplet and the RQA parameters of RP, it is observed that higher the recurrence rate along with high determinism can cause severe damage to the insulating material. Structural analysis using ATR-FTIR and pyrolysis-GC/MS studies reveal significant functional group variation on surface of silicone rubber, especially when the number of cycles of corona ageing is more. [ABSTRACT FROM AUTHOR]

Particulate organic matter (POM) chemistry and microbial degraders are important determinants of soil carbon (C) mineralization, but the effects of their interactions on C mineralization are largely unknown. Two contrasting soils with different POM chemical composition from karst ecosystems were sampled, sterilized, and cross-inoculated with microorganisms for 124 days to explore the relationships between POM chemical composition, microbial community composition, and soil organic C (SOC) mineralization. Pyrolysis-gas chromatography/mass spectrometry analysis was used to determine POM chemistry, and phospholipid fatty acid (PLFA) analysis was used to characterize the soil microbial community. Microbial cross-inoculation showed that the microbial community composition did not change in response to changes in soil C and that the relatively labile POM components, e.g. , fatty acids and n -alkenes, explained 61.2% of the variation in microbial community composition. Microbial community composition, such as PLFAs cy19:0, i17:0, 10Me16:0, and 18:2ω6,9c, strongly influenced POM chemical composition, explained 94.5% of the variation in POM chemical composition. These results indicated that soil microbial communities could adapt to changes in POM and served as main drivers of POM chemistry alterations. In addition, mineralized soil C (% of SOC) was significantly influenced by microbial community composition, soil source, and their interactions. Redundancy analysis and Mantel tests further revealed that SOC mineralization was strongly affected by POM chemical composition ( e.g. , the content of ketones and p -hydroxyphenyl) and microbial community composition ( e.g. , the content of PLFAs 16:1ω7c and 10Me16:0), and that the influence of microbial community composition on SOC mineralization was highly dependent on POM chemical composition, suggesting that the interactions of POM chemistry and microbial community composition mediate SOC mineralization. These analyses indicate a tight relationship between POM chemistry and microbial community composition, and highlight the importance of their interactions in mediating the persistence of organic matter in karst soils. [ABSTRACT FROM AUTHOR]

The stability of soil organic matter (OM) in Amazonian anthropogenic soils, Terra Preta de Índio (TPI), is still not completely understood. The large contribution from black carbon (BC) and minerals to these soils is well-known; OM stability is therefore frequently explained by these properties, providing intrinsic recalcitrance (BC) and chemical protection against decomposition (OM-mineral associations), but the relative importance of both mechanisms that underlie the stability are not yet understood. In order to better understand the sources and decay processes of soil OM in these soils, we studied the molecular composition using pyrolysis gas-chromatography/mass-spectrometry. To this end, several soil OM fractions of samples from two TPI soils and an adjacent Xanthic Acrisol that served as a reference soil (REF) were studied (0–2 m depth). A sequential fractionation was applied in order to better understand the composition of soil OM pools with different association to the soil matrix. The studied soil OM fractions included the free light fraction (FLF; i.e., charcoal and litter), the occluded light fraction (OLF; charcoal and litter within aggregates), 0.1 M NaOH extractable OM (EX; comparable with the combined humic acid and fulvic acid fractions), and the remaining residue (RES; treated with HF/HCl; comparable with the humin fraction). The largest contribution to the total soil OM was found for EX and/or RES, the sum of which varied between 79% and 98% (Ave. 90.8%, n = 18). The minor contribution from the OLF (Ave. 4.4%) indicates that stabilisation within aggregates was not a major factor that contributed to OM stability in the studied profiles. Differences in molecular composition between the fractions were larger than those between profiles or with depth. The EX fraction showed the lowest contribution from plant (lignin phenols) and BC (PAHs, indenes, aromatics) derived products. The RES fraction showed a significantly larger contribution from BC related pyrolysis products compared to the EX. This non-extractable BC that is present in the RES after removal of the light fractions may reflect preferential binding of PAHs to minerals or, alternatively, the presence of highly condensed macromolecular polyaromatic structures. Changes with depth within the EX and RES fractions showed a larger contribution from products derived from BC in the anthropogenic horizons. Furthermore, the OM composition in EX and RES indicated that the degree of degradation of OM in anthropogenic horizons was relatively low. Apart from these similarities for anthropogenic horizons, the chemical composition of soil OM also showed large differences between both TPI soils. TPI-1 showed large variation between horizons while TPI-2 showed only minor changes with depth; this may be related to different phases of human occupation with time and/or a different soil usage. [ABSTRACT FROM AUTHOR]

The pyrolysis of four kinds of common polyurethanes comprising a rigid and a flexible foam, a cast elastomer, and a thermoplastic polyurethane (TPU) was investigated by thermogravimetric analysis and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). All samples are based on methylene diphenyl diisocyanate (MDI), with polyether polyols as the soft segment of the foams and polytetrahydrofuran as the soft segment of the cast elastomer and TPU. Each polyurethane degrades in a two-step manner with a high correlation between the polymer structure and the mass loss in each step. Two kinetic modeling approaches based on either parallel or consecutive reactions were successfully applied to describe the pyrolytic degradation. The virgin polymers and pyrolysis intermediates obtained from thermogravimetry with isothermal segments at different temperatures of 350–450 °C were investigated by ATR-FTIR. Both foams exhibit retention of feedstock nitrogen in a carbonaceous intermediate while no significant residue formation and nitrogen retention are observable for cast elastomer and TPU pyrolysis. Aromatic amines in the foam pyrolysis intermediates point to the formation of a secondary polymer originating from the urethane segments in the course of the degradation. In Py-GC/MS, the foams yield nitrogen-carrying fragments of the MDI. MDI and 1,4-butanediol are regenerated from TPU pyrolysis, indicating different degradation pathways. CE pyrolysis also releases 1,4-butanediol but no nitrogen-carrying compounds are detectable. This work demonstrates the individuality of polyurethane materials in terms of their pyrolysis behavior and released products. Potential high-value products are identified in pyrolysis at laboratory scale. The findings of this study underline the need for a comprehensive examination of polyurethane pyrolysis with differentiation of polyurethane composition and morphology to optimize technical scale polyurethane pyrolysis. • Model polyurethanes were investigated by thermogravimetry, Py-GC/MS and ATR-FTIR. • Pyrolytic degradation mechanisms are highly dependent on the polyurethane composition. • Residue formation is linked to aromatic nitrogen carrying pyrolysis intermediates. • Two kinetic models were successfully applied to describe the polyurethane pyrolysis. [ABSTRACT FROM AUTHOR]

Microplastics (MP) including tire wear particles (TWP) are ubiquitous. However, their mass loads, transport, and vertical behavior in water bodies and overlying air are never studied simultaneously before. Particularly, the sea surface microlayer (SML), a ubiquitous, predominantly organic, and gelatinous film (<1 mm), is interesting since it may favor MP enrichment. In this study, a remote-controlled research catamaran simultaneously sampled air, SML, and underlying water (ULW) in Swedish fjords of variable anthropogenic impacts (urban, industrial, and rural) to fill these knowledge gaps in the marine-atmospheric MP cycle. Polymer clusters and TWP were identified and quantified with pyrolysis-gas chromatography-mass spectrometry. Air samples contained clusters of polyethylene terephthalate, polycarbonate, and polystyrene (max 50 ng MP m -3 ). In water samples (max. 10.8 μg MP L -1 ), mainly TWP and clusters of poly(methyl methacrylate) and polyethylene terephthalate occurred. Here, TWP prevailed in the SML, while the poly(methyl methacrylate) cluster dominated the ULW. However, no general MP enrichment was observed in the SML. Elevated anthropogenic influences in urban and industrial compared to the rural fjord areas were reflected by enhanced MP levels in these areas. Vertical MP movement behavior and distribution were not only linked to polymer characteristics but also to polymer sources and environmental conditions.

• Molecular features of SOM fractions after forest conversion from deciduous to spruce. • Ecological and environmental factors reflected in the composition of SOM fractions. • Molecular changes with depth, decomposition, litter inputs, and soil process domain. • Consistent molecular shifts from fractions with and without alkaline extraction. The molecular composition of soil organic matter (SOM) contains key information on the persistence of soil carbon (C) in relation to changes in vegetation and environmental factors. Depending on the ecosystem, analytical method and specific objectives, many SOM fractions and numerous fractionation schemes have been proposed to study soil C. However, the molecular composition and environmental significance of those different SOM fractions have not yet been compared systematically. We use a reverse fit approach to fill this knowledge gap: i.e. we chose a study area with a well-known land history to assess which information is stored in the most frequently analysed SOM fractions. The Gaume forest (Belgium) is an ancient deciduous forest (>200 years) in which small stands were converted to Norway spruce (Picea abies) 40–50 years ago. Those stands are located along a lithological gradient in soil buffering capacity. We investigated the molecular composition of bulk mineral soil samples and five organic SOM fractions by pyrolysis gas chromatography/mass spectrometry (Py-GC/MS). The SOM fractions included particulate OM (POM), water extractable OM (WEOM), and fractions obtained by alkaline extraction, including the traditionally used humic acid (HA) and fulvic acid (FA) and the total base extract from which they are obtained (BE). Our results indicate that pyrolysates of bulk mineral soil did not prove useful to reflect environmental changes after forest stand conversion. Principal Component Analysis indicated that within each organic fraction similar changes occurred when comparing soil depths, degree of SOM decomposition, litter inputs, and soil buffering capacity. However, only the HA and BE appeared successful in capturing all these processes: the degree of SOM decomposition was not expressed in pyrolysates from the POM, differences in litter input between forest stand types were not evidenced in the WEOM, and effects of buffering capacity were not demonstrated in the WEOM and FA fractions. Thus, the molecular composition of different SOM fractions can be used complementary to each other to study environmental and ecological effects of forest stand conversion on soil C dynamics. [ABSTRACT FROM AUTHOR]