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Volatile organic compounds (VOCs) generated from naturally aged Japanese hanging scrolls and their model samples were measured using solid-phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS) to clarify the effect of different painting papers and raw materials on the degradation state of hanging scrolls. VOC-based degradation markers were identified and their applicability was considered for degradation evaluations of actual Japanese hanging scrolls. The relative peak areas of different VOC groups were calculated by normalising their peak areas to the total peak area of long-chain hydrocarbons. When a painting paper was immersed in a CuSO4・5H2O solution, or coated with an alum solution, the relative peak areas of furfural and carboxylic acids increased after accelerated ageing, while these relative peak areas decreased when animal glue was applied, indicating that animal glue inhibited the generation of VOCs. When the painting paper containing Cu2+ was stacked with lining paper, furfural and carboxylic acids migrated into the lining paper with ageing. Animal glue coated on the painting paper retarded this migration into the lining paper. For the lining paper coated with wheat starch paste, the relative peak areas of furfural, carboxylic acids, and aliphatic aldehydes did not change significantly with ageing, indicating that wheat starch paste did not contribute to paper degradation, although these relative peak areas increased when aged wheat starch paste was applied. These results indicate that the targeted VOCs are valid degradation markers of Japanese hanging scrolls. [ABSTRACT FROM AUTHOR]

[Display omitted] • Identification of asphalt markers with pyrolysis mass spectrometry techniques. • Cooking with drying oil leads to the disappearance of asphalt markers. • Py-GCxGC/MS used for the first time on asphalt containing oil paints. Bitumen brown oil paint reconstructions based on 19th century production records from the British colourman Winsor & Newton were analysed using thermally assisted methylation with tetramethylammonium hydroxide (Py-TMAH-GC/MS), and pyrolysis comprehensive two-dimensional gas chromatography (Py-GCxGC/MS). Reconstructions were compared with the starting material, Trinidad Lake asphalt (TLA), to determine how detectable this asphalt is after heat processing in lead treated linseed oil. The use of brown paint containing asphalt/bitumen (the names are used interchangeably) was blamed for severe film-forming defects in 18th and 19th century oil paintings, yet this material has rarely been identified in earlier studies of historical paintings. This research offers a possible explanation for the paucity of evidence as it reveals that asphalt markers identified in the TLA disappear in the first stage of reconstructing bitumen brown oil paint. [ABSTRACT FROM AUTHOR]

Abstract: Infrared image furnace ion-attachment mass spectrometry (IIF-IAMS) experiments have been conducted to elucidate the effects of copper(II) chloride on the formation of aromatic compounds during the pyrolysis of polyethylene. Under the time-resolved pyrolysis conditions of IIF-IAMS, the effects of CuCl2 were measured to compare the variation in ratios of alkenes and aromatics during polyethylene thermal degradation when pyrolysis temperature was increased. Thermogravimetry experiments and X-ray powder diffraction analysis conducted under similar conditions to those used for IIF-IAMS enabled us to characterize the oxidation states of copper prevailing during the thermal degradation process of polyethylene in the presence of CuCl2. Reduction of Cu(II) into Cu(I) during the pyrolysis process was characterized. The IIF-IAMS method demonstrates its advantage for on-line detection of reaction products during time-resolved pyrolysis experiments. [ABSTRACT FROM AUTHOR]

On the basis of ongoing research conducted on the clarification of processes responsible for lubricant degradation in the environment of piston grooves in exhaust gas recirculation (EGR) diesel engines, an experimental investigation was aimed to develop a kinetic model, which can be used for the prediction of lubricant oxidative degradation correlated with endurance test conducted on engines. Knowing that base oils are a complex blend of paraffins and naphthenes with a wide range of sizes and structures,. their chemistry analysis during the oxidation process can be highly convoluted. In the present work, investigations were carried out with the squalane (C30H62) chosen for its physical and chemical similarities with the lubricant base oils used during the investigations. Thermooxidative degradation of this hydrocarbon was conducted at atmospheric pressure in a tubular furnace, while varying temperature and duration of the tests in order to establish an oxidation reaction rate law. The same experimental procedures were applied to squalane doped with two different phenolic antioxidants usually present in engine oil composition: 2,6-di-tert-butyl-4-methylphenol and octadecyl-3-(3,5-di-tert-butyl-4- hydroxyphenyl)propionate. Thus, the effect of both antioxidants on the oxidation rate law was investigated. Data analysis of the oxidized samples (Fourier transform infrared spectroscopy and gas chromatography/mass spectrometry) allowed rationalization of the thermo-oxidative degradation of squalane. The resulting kinetic modeling provides a practical analytical, tool to follow the thermal degradation processes, which can be used for prediction of base oil hydrocarbon aging. If experiments confirmed the role of phenolic additives as an effective agent to lower oxidation rates, the main results lie in the observation of a threshold temperature where a reversed activity of these additives was observed. [ABSTRACT FROM AUTHOR]

Abstract: The neutral active products extracted from a microwave discharge in CF4/He were analyzed by mass spectrometry. Free radical species such as CHF2, CF2, and CF3 were detected and analyzed for the first time using the Li+ ion attachment mass spectrometry technique. We examined the effects of varying the MW power and the feed gas composition on the production of an intense flow source of CHF2, CF2, and CF3 radicals as well as many other products. A radical chain reaction is postulated as the mechanism for the formation of the observed polymeric products. [Copyright &y& Elsevier]

Focuses on the characterization of free organic radicals using mass spectrometry. Parallel directions followed by the first free radical studies by mass spectrometry; Instrumental developments for radical studies.

In this study, we report the use of pyrolysis-GCxGC/MS profiles for an optimized treatment of data issued from pyrolysis-GC/MS combined with the automatic deconvolution software Automated Mass Spectral Deconvolution and Identification System (AMDIS). The method was illustrated by the characterization of marker compounds of East Asian handmade papers through the examination of pyrolysis-GCxGC/MS data to get information which was used for manually identifying low concentrated and co-eluting compounds in 1D GC/MS data. The results showed that the merits of a higher separation power for co-eluting compounds and a better sensitivity for low concentration compounds offered by a GCxGC system can be used effectively for AMDIS 1D GC/MS data treatment: (i) the compound distribution in pyrolysis-GCxGC/MS profiles can be used as “peak finder” for manual check of low concentration and co-eluting compound identification in 1D GC/MS data, and (ii) pyrolysis-GCxGC/MS profiles can provide better quality mass spectra with observed higher match factors in the AMDIS automatic match process. The combination of 2D profile with AMDIS was shown to contribute efficiently to a better characterization of compound profiles in the chromatograms obtained by 1D analysis in focusing on the mass spectral identification.Graphical abstract [ABSTRACT FROM AUTHOR]

Cellulose paper degradation products forming in the 'tideline' area at the wet-dry interface of pure cellulose paper were analyzed using gas chromatography-electron ionization-mass spectrometry (GC-EI-MS) and high-resolution electrospray ionization-mass spectrometry (ESI-MS, LTQ Orbitrap) techniques. Different extraction protocols were employed in order to solubilize the products of oxidative cellulose decomposition, i.e., a direct solvent extraction or a more laborious chromophore release and identification (CRI) technique aiming to reveal products responsible for paper discoloration in the tideline area. Several groups of low molecular weight compounds were identified, suggesting a complex pathway of cellulose decomposition in the tidelines formed at the cellulose-water-oxygen interface. Our findings, namely the appearance of a wide range of linear saturated carboxylic acids (from formic to nonanoic), support the oxidative autocatalytic mechanism of decomposition. In addition, the identification of several furanic compounds (which can be, in part, responsible for paper discoloration) plus anhydro carbohydrate derivatives sheds more light on the pathways of cellulose decomposition. Most notably, the mechanisms of tideline formation in the presence of molecular oxygen appear surprisingly similar to pathways of pyrolytic cellulose degradation. More complex chromophore compounds were not detected in this study, thereby revealing a difference between this short-term tideline experiment and longer-term cellulose aging. [ABSTRACT FROM AUTHOR]

We tested the performance of pyrolysis-comprehensive two-dimensional gas chromatography/mass spectrometry in the course of our cultural heritage studies, and compared its potentialities for the characterization of traditional East Asian handmade papers with those previously obtained by pyrolysis-gas chromatography/mass spectrometry. The evaluation of the two methods was conducted in considering the number of detected peaks, the compounds separation, the sensitivity, and the identification of marker compounds. The results showed that the number of plant markers (triterpenes and phytosterols) detected in a Japanese kozo reference paper was improved in the pyrolysis fingerprint. With a gain in sensitivity in the order of six, the case study of a museum sample confirmed that pyrolysis-comprehensive two-dimensional gas chromatography/mass spectrometry is more efficient for a reliable identification of museum collections samples and/or archaeological samples where tiny quantities of materials are the rule. The present study has been successful in refining a micro-destructive method based on analytical pyrolysis for the characterization of traditional East Asian handmade papers using pyrolysis-comprehensive two-dimensional gas chromatography/mass spectrometry. [ABSTRACT FROM AUTHOR]

Abstract: Pyrolysis experiments were conducted to elucidate the effects of metal chlorides on the thermal degradation of low-density polyethylene on a continuous pyrolysis temperature range of 600°C to 1100°C. The present work focusses on the ratio of aromatics generated on increasing the pyrolysis temperature in the presence of metal salts, iron(II), iron(III) and copper(II) chlorides. It was observed that beside α,ω-dienes, α-olefins and n-alkanes which are usually observed during the thermal decomposition of polyethylene, the level of aromatics noticeably increases with the addition of metal salts. At high temperatures, the formation of these aromatics took place in such a way that they become the major products when polyethylene is pyrolyzed in presence of FeCl3 and CuCl2. Quantification of the effect of metal salts has been tempted comparing the variation of the ratio of aromatics with pyrolysis temperatures. Mechanisms responsible for the formation of these aromatics in presence of metal salts have been tentatively investigated. They are proposed to result from cyclization/dehydrogenation reactions similar to those observed during the thermal decomposition of polyethylene, but with an increased efficiency due to the metal salts. [Copyright &y& Elsevier]

Korean hand papermaking is a renowned cultural tradition in the Korean peninsula. It is still practiced while scientific analysis of paper itself from a large data set is rare. In this study, a set of more than three hundred Korean handmade papers, collected in a reference collection book Hanji: Korean handmade paper, were chemically investigated, and their property data such as colour, pH, grammage, thickness, tensile strength, folding endurance were statistically analysed in order to determine general features for Korean papers. The influence of different paper sheet formation methods (Heullimtteugi vs Gadumtteugi) were revealed by multivariate data analysis and the chemical profiles of raw materials were studied by pyrolysis–gas chromatography/mass spectrometry (Py-GC/MS). The Korean handmade paper samples display colour gamut in the colour space L* (69.9–95.9), a* [(−3)-3], b* (0–20), most have neutral/alkaline pH values. Paper density, fiber orientation and physical properties are influenced by the sheet formation techniques. For instance, Gadumtteugi tends to produce papers with strong fiber orientation while Heullimtteugi produces papers with more evenly distribution of fibers. In addition, Py-GC/MS analysis results show that paper mulberry fibers contain less intensity lignin monomers and more terpenic compounds in comparison with gampi and mitsumata fibers. This study provides paper analysis from large sample set, statistics reveal that the material preparing and making craft determined the paper structure which reflected in their physical properties. These properties influenced paper performance and applications in art creations as well as relics conservation and restoration. The characterized paper sample database could be used for handmade paper studies in East Asian region. Consequently, this study contributes to a better understanding of contemporary Hanji properties as well as improves knowledge on handmade papers from the Korean peninsula. [ABSTRACT FROM AUTHOR]

The present knowledge on chemical communication in springtails (Collembola), one of the two most abundant invertebrate groups living in soil and environments in tight contact with soil (e.g. plant litter, moss), is reviewed here. Chemical communication in an environment where light is absent or dimmed becomes a prominent driver of trophic and non-trophic interactions between soil organisms at a time when better knowledge on the biological determinants of soil communities is required. Like insects and many other arthropods, collembolan individuals of the same population intercommunicate by pheromones, which allow them signalling a risk or clustering in places favourable for feeding, mating, moulting and ovipositing. Olfaction is also used to select preferred food and mates. Researches so far conducted allowed discerning common trends in the role and chemical composition of odour blends used by Collembola. However, much more needs to be done before reaching straightforward conclusions about chemical communication issues at evolutionary and community levels, making this domain even more rewarding. [ABSTRACT FROM AUTHOR]

An analytical approach based on the multivariate analysis of on-line pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) data is proposed for the identification of traditional East Asian handmade papers from different fiber material origins. This approach utilized several biomarkers detected during the Py-GC/MS analysis of paper samples. At first, the total ion chromatogram (TIC) was taken as the response and then the extracted ion chromatograms (EICs) were considered to improve the discrimination of papers. The influence of different data pretreatments (raw responses vs. normalized values) including different weightings of the variables (weighting as 1 vs. weighting as 1/STD, where STD stands for standard deviation) for principal component analysis was also investigated. The results showed that compared to the commonly used microscopy techniques, the Py-GC/MS technique proved to be able to discriminate against handmade paper materials that have similar microscopic morphologies such as Morus species vs. Broussonetia species. The data pretreatment influenced PCA modeling: the analysis based on normalized values showed more interpretable PCA group features for Moraceae species. PCA without weighting resulted unsurprisingly in discrimination through the presence of high intensity response biomarkers, while when applying weight as 1/STD, a PCA loading plot was shown to provide a group of compounds, most of them being present at low levels, to be discriminating. Additionally, the characteristic EICs can provide a data matrix for statistical analysis avoiding the interference from a co-eluting compound and background compared to the data matrix obtained from the TIC. As a result, a quick Py-GC/MS based handmade paper identification procedure using PCA modeling of the characteristic EICs was proposed for the first time in the identification of traditional East Asian handmade papers. This procedure could be very beneficial for cultural heritage applications. [ABSTRACT FROM AUTHOR]

A new approach based on online pyrolysis-comprehensive gas chromatography/mass spectrometry (Py-GCxGC/MS) is introduced for analysis of lacquer saps with potential applications to analysis of Asian lacquers. The bidimensional GCxGC separation demonstrated its benefits for characterization of the markers of lacquer saps, alkylhydrocarbons, alkylbenzenes, alkylphenols, and alkylcatechols, in a visual way not attainable in monodimensional Py-GC/MS analysis. Moreover, the potentiality offered by GCxGC allows the separation of regioisomers difficult to obtain with a monodimensional separation. Under these circumstances, urushiol (Japanese, Chinese), laccol (Vietnamese), and thitsiol (Myanmar) lacquer sap films were differentiated by their marker fingerprints with a limit of detection in the low μg range. Additionally, thermally assisted pyrolysis with tetramethylammonium hydroxyde (TMAH) clearly differentiated the alkylcatechol markers of the four lacquer samples investigated, with a net separation of stereoisomers particularly well exemplified in the case of the Myanmar lacquer sample. The proposed Py-GCxGC/MS approach greatly facilitates the analysis of Asian lacquer saps, and is very promising for sensitive detection of lacquers in archaeological artifacts. [ABSTRACT FROM AUTHOR]

An analytical method based on the combination of on-line pyrolysis-comprehensive two-dimensional gas chromatography/mass spectrometry and multivariate analysis for a direct characterization of traditional East Asian handmade papers is presented here. The method was applied to three kinds of widely used handmade papers in East Asia followed by an attempt of identification of ancient lining papers belonging to museum samples of unknown origin. The results indicated that Py-GCxGC/MS, together with multivariate data analysis, was more efficient and reliable compared to the compound presence/absence analysis to meet the challenging search for organic markers in rare cultural heritage materials. The established method showed promises as an efficient analytical tool for the characterization of artwork and culture heritage materials and in filling the lacuna for papermaking fiber analysis which is currently almost entirely relied on microscopy analysis. Results also revealed that two-dimensional techniques could constitute an efficient approach for the analysis of complex artwork samples to circumvent the limitation of materials at disposal in cultural heritage studies. [ABSTRACT FROM AUTHOR]

The presence of trace levels of organic contaminants in the environment is currently an environmental concern. When these contaminants are subjected to environmental transformations, environmental transformation products (ETPs) are obtained, whose structures often remain unknown. The absence of information concerning these new compounds makes them unavailable and consequently makes their environmental detection as well as their (eco)toxicological study impossible. This report describes a multidisciplinary approach that seeks to both anticipate the fate and evaluate the impact of organic environmental contaminants. Our approach consists of three steps. First, isolated and fully characterized transformation products (TPs) of the parent molecule are obtained. In the second step, the parent molecule is subjected to environmentally relevant transformations to identify plausible ETPs. The detection of previously characterized TPs allows the concomitant identification of plausible ETPs. The third step is devoted to the toxicological evaluation of the identified plausible ETPs. Such an approach has recently been applied to furosemide and has allowed the identification of its main TPs. This report now seeks to identify and evaluate toxicologically plausible ETPs of this drug, which is also known as an environmental contaminant. [ABSTRACT FROM AUTHOR]

Highlights: [•] Photooxidation of acetochlor – the characterization of photodegradation products is achieved using LC–MS and GC–MS. [•] Elucidation of structures using complementary experiments (MS/MS, high resolution experiments, deuterated compound). [•] Quantitative structure–activity relationship (QSAR) approach – potential toxicity effect of acetochlor and its by-products. [Copyright &y& Elsevier]

Oriental lacquer has been used in Asian countries for thousands of years as a durable and aesthetic coating material for its adhesive, consolidating, protective and decorative properties. Although these objects are made from an unusual material in Occident, Western museum collections host many lacquerwares. Curators, restorers and scientists are daily confronted with questions of their conservation and their alteration. The characterization of their conservation state is usually assessed through visual observations. However deterioration often starts at the microscopic level and cannot be detected by a simple visual inspection. Often, ageing and deterioration of artworks are connected to physical, mechanical and chemical transformations. Thus new insight into alteration of lacquer involves the monitoring of macro-, microscopic and molecular modifications, and this can be assessed from physico-chemical measurements. Non-invasive (microtopography and Scanning Electron Microscopy – SEM) and micro-invasive (infrared micro-spectroscopy using a synchrotron source – SR-μFTIR) investigations were performed to study the degradation processes of lacquers and evaluate their level of alteration. In particular, spectral decomposition and fitting procedure were performed in the 1820–1520 cm−1 region to follow the shift of the C=O and C=C band positions during lacquer ageing. The present work proves the potential of this physico-chemical approach in conservation studies of lacquers and in the quantification of the state of alteration. It evidences chemical phenomena of alteration such as oxidation and decomposition of a lacquer polymeric network. It also demonstrates for the first time the degradation front of artificially aged lacquer and the chemical imaging of a more than 2000 years old archaeological lacquer by using SR-μFTIR. [ABSTRACT FROM AUTHOR]

Abstract: The widespread occurrence of chlorinated herbicides and their degradation products in the aquatic environment raises health and environmental concerns. As a consequence pesticides, and to a lesser degree their degradation products, are monitored by authorities both in surface waters and drinking waters. In this study the formation of degradation products from ultraviolet (UV) treatment of the three chloroacetamide herbicides acetochlor, alachlor and metolachlor and their biological effects were investigated. UV treatment is mainly used for disinfection in water and wastewater treatments. First, the chemical structures of the main UV-degradation products were identified using gas chromatography coupled with mass spectrometry and liquid chromatography–mass spectrometry. The main transformation reactions were dechlorination, mono- and multi-hydroxylation and cyclizations. The ecotoxicity of the mixed photoproducts formed by UV-treatment until 90% of the original pesticide was converted was compared to the toxicity of chloroacetamides using the green alga Pseudokirchneriella subcapitata, the crustacean Daphnia magna and the marine bacteria Vibrio fischeri as test organisms. UV-treatment of alachlor and metolachlor increased the toxicity compared to the parent compounds while an equal toxicity was found for photolysis products of acetochlor. This suggests that toxic photodegradation products are generated from chloroacetamides under UV-treatment. An important perspective of this finding is that the photolysis products are at least as toxic as the parent compounds. [Copyright &y& Elsevier]

[Display omitted] • Formulation of beeswax-rosin mixture can be estimated without the use of reagent. • Calibrations curves based on model samples have been plotted using IR and DSC data. • Quantification of the impact of third-party materials. • Compositional determination of historical sealants from the CAC of the Paris MNHN. Wet collections sealants are historical materials that are essential for a sustainable preservation of specimens in fluid. Yet little is known about their composition, apart what can be found in technical records. Few scientific studies are dedicated to the identification of these materials that often correspond to complex mixtures. This work aims at facilitating the characterization of beeswax-rosin mixtures used for sealing wet collections. It explores the possibilities to quantify the proportions of beeswax-rosin mixtures by Differential Scanning Calorimetry (DSC) and Attenuated Total Reflectance Fourier Transformed mid-Infrared Spectroscopy (ATR-FTIR), two easy-to-run methodologies that require small samples. First these techniques were tested on model beeswax-rosin mixtures and appeared complementary. Then they were implemented on historical sealants and cross-checked with Pyrolysis Gaz Chromatography Mass Spectroscopy (Py-GC/MS) measurements, giving promising results. The impact, on the results, of ageing or of possible addition of third-party fatty materials such as animal fat or vegetal oil is also discussed. [ABSTRACT FROM AUTHOR]

Aqueous solutions of metolachlor and metolachlor-d6 were photolyzed with UV-visible radiations. The structures of 15 by-products of metolachlor were determined through gas chromatography-mass spectrometry analyses using electron and chemical ionization combined with multistage mass spectrometry. The photolysis by-products of metolachlor resulted mainly from dehalogenation and hydroxylation, in some cases accompanied by cyclization. In silico tests for toxicity prediction showed that the toxicity of some photolysis products is expected to be greater than that of metolachlor. Persistence studies showed that the by-product relative abundances vary in large amounts with the irradiation time. The post-photolysis evolution of the solution was also studied, in order to determine the persistence of the main by-products. It allowed to establish that most of the by-products can be found more than 12 h after the end of the photolysis, which is of a great concern as treated water is generally available for consumption only a few hours after treatment in most of industrial processes. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: The identification of degradation products generated upon photolysis of estrone (E1), a natural estrogenic hormone, under simulated UV irradiation conditions was addressed by the use of LC-Q-TOF mass spectrometry. The structures of the main degradation products were elucidated, demonstrating how the use of model molecules 5,6,7,8-tetrahydro-2-naphtol (THN), 2-methylcyclopentanone (MCP), labeled molecule estrone D4 (E1-D4), the investigation of the fragmentation pathways of the parent E1, the concurrent use of CID and exact mass measurements permit the characterization of structural modifications induced by photodegradation processes. In the present study, we identified nine major by-products of which seven photoproducts correspond to E1H+ modified in positions other than the C-2, C-4 and C-16 of E1. Most of them showed one to three additional hydroxylations preferentially located on the aromatic ring of the parent E1, which confirms that these products may present environmental risk. Applications to real water samples have been conducted to extend the validity of the present study to environmental samples. [Copyright &y& Elsevier]

Abstract: This paper focuses on the identification of several chemical markers of vegetal species of Oriental lacquers with the aim at providing a methodology consistent with sampling restrictions necessarily applied in the field of cultural heritage. The method proposed is based on rapid and easy single step thermally assisted hydrolysis–methylation (THM) pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) analysis that can be carried out with a minimum amount of matter (typically 10μg for a sample collected on a museum or an archaeological object). The main contribution of this study is to provide multiple molecular criteria for discriminating the three Asian species used for making lacquers, namely Rhus verniciflua Stokes, Rhus succedanea and Melanorrhoea usitata. Because these trees grow in specific areas, identifying the species involved in ancient lacquer coatings also provides geobotanical data and fruitful information on the exchange networks and trading routes developed by ancient societies. With this purpose, a systematic study of all pyrolysis products of lacquer coatings was carried out on modern dried lacquer films from authentified provenance. It was demonstrated that the whole pyrolysis products play a significant role in identifying the vegetal species. The chemotaxonomic value of homologous series of alkanes, alkenes and benzene derivatives, rarely explored until now, was assessed. It was shown that the combination of data related to five distinct groups of pyrolytic markers (composition and/or distribution of alkanes, alkenes and benzene, alkenyl-, alkylcatechol and phenol derivatives) provided new strong criteria to establish vegetal origin and provenance of Asian artworks, even though they have been largely altered over time. Case studies of archaeological Chinese lacquered artefacts and Japanese Buddhistic altar were thereafter successfully investigated to address informative potential and efficiency of these criteria on ancient and degraded lacquer coatings. [Copyright &y& Elsevier]

This article describes the strange behavior of the widely used herbicide metolachlor under chemical ionization conditions in a hybrid source ion trap mass spectrometer in gas chromatography/mass spectrometry (GC/MS) coupling. With the use of ammonia as the reagent gas, metolachlor provides a chlorinated ion at m/z 295/297, almost as abundant as the protonated molecule at m/z 284/286, which cannot be isolated to perform tandem mass spectrometry (MSn) experiments. Curiously, this ion at m/z = M + 12 is not observed for the herbicides acetochlor and alachlor, which present very similar chemical structures. The chemical structure of the m/z 295/297 ions and the explanation of the observed phenomenon based on the metastable behavior of these ions were elucidated on the basis of experiments including isotopic labeling and modifications of the operating conditions of the ion trap mass spectrometer. This work allows one to give new recommendations for an optimized use of hybrid source ion trap mass spectrometers. [ABSTRACT FROM AUTHOR]

A well-established ion attachment mass spectrometer (IAMS) is combined with an in-house single-atom infrared image furnace (IIF) specifically for thermal analysis studies. Besides the detection of many chemical species at atmospheric pressure, including free radical intermediates, the ion attachment mass spectrometer can also be used for the analysis of products emanating from temperature-programmed pyrolysis. The performance and applicability of the IIF-IAMS is illustrated with poly(tetrafluoroethylene) (PTFE) samples. The potential of the system for the analysis of oxidative pyrolysis is also considered. Temperature-programmed decomposition of PTFE gave constant slopes of the plots of temperature versus signal intensity in a defined region and provided an apparent activation energy of 28.8 kcal/mol for the PTFE decomposition product (CF2)3. A brief comparison with a conventional pyrolysis gas chromatography/mass spectrometry system is also given. [ABSTRACT FROM AUTHOR]

The applicability of the kinetic method to the determination of the basicity of bidentate molecules has been assessed by considering several molecules M previously studied by equilibrium method (M=acetone (1), 1,3-propanediol (2), glycerol (3), 1,4-butanediol (4), 1,3-propanolamine (5), 1,4-butanolamine (6), 1,3-propanediamine (7) and 1,4-butanediamine (8)). Protonated adducts [MHBi]+ (where Bi is a reference base) were produced by electrospray ionisation and analysed by tandem quadrupole mass spectrometry. Application of the classical correlation of the natural logarithm of the ratio of peak intensities, ln([MH]+/[BiH]+), with either the proton affinities (PA) or the gas phase basicities (GB) of the reference bases Bi to deduce PA(M) or GB(M) has been examined. It is confirmed that only the use of several experiments at different collision energies (“extended” or “isothermal point” methods) may lead to meaningful results. Good agreement is observed between the PA(M) values tabulated or obtained from the isothermal point for molecule M=1 and 5–8. However, the present PA values appear to be different from that obtained by equilibrium method in the case of diols 2–4. It is generally observed that the measured “apparent” protonation entropies of all the bifunctional molecules examined are significantly less than that obtained by equilibrium methods. [Copyright &y& Elsevier]

The author regrets at the beginning of the sub-section "Sex pheromones" (page 428 of the published version) within the section "The use of pheromones, allomones and kairomones by Collembola" [ABSTRACT FROM AUTHOR]