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Abstract: A new pyrolysis–GC/MS system incorporating with on-line micro-ultraviolet (UV) irradiation was developed to make rapid evaluation of the synergistic material deterioration during UV irradiation under thermal and oxidative atmospheres. The basic effectiveness of the system was demonstrated by polystyrene, polypropylene and polycarbonate as the test samples. The volatile products evolved during deterioration of the polymers were analyzed on-line by thermal desorption GC/MS, and then the residual degraded polymers were analyzed by evolved gas analysis (EGA) and/or Py–GC/MS to obtain specific thermograms and pyrograms. Based on these results, the deterioration mechanism of the polymeric materials during irradiation under thermal and oxidative atmosphere can be evaluated using a sub-milligram polymer sample within a relatively short period of time. [Copyright &y& Elsevier]

The flame retardant mechanism for silicone rubber induced by adding ppm order of a platinum compound, platinum (0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex was studied by analytical pyrolysis techniques and alkaline hydrolysis gas chromatography. The thermal degradation measurement of the flame retardant silicone rubber sample (FR-SR) indicated that a considerable amount of methane was evolved from the FR-SR sample at around 400–800 °C while formations of cyclic siloxanes were fairly suppressed in comparison with that from the control SR sample. On the other hand, on the gas chromatogram of the hydrolysis products from the FR-SR residue samples thermally treated over 400 °C, significant amounts of characteristic products reflecting the cross-linking structures generating from methylene-bridge and trifunctional siloxane structures in the polymer chains were observed. These results suggest that the thermal decomposition of the FR-SR material is strongly suppressed by the formation of the cross-linking structures induced by the platinum compound during combustion, which leads to its flame retardancy. [Copyright &y& Elsevier]

Abstract: A pyrolysis-GC/MS system incorporating with micro-UV irradiator (Xe–Hg lamp) was applied to the evaluation of the weatherability of the acrylic coating paints for house exterior walls. The deterioration of the materials during UV irradiation under thermal, and oxidative atmosphere was evaluated within a relatively short period of time with evolved gas analysis-mass spectrometry (EGA-MS) using a sub-milligram polymer sample. The EGA-MS thermograms indicated that both micro-UV irradiator with Xe–Hg lamp and weather meter with metal halide lamp caused similar photo, thermal, and oxidative degradation to the coating paint samples. Strong correlations between the results obtained by the UV/Py-GC/MS and that obtained by conventional weathering test using metal halide lamp was observed. It was suggested that UV/Py-GC/MS method could be used for compensating the conventional method by reducing the test period. [Copyright &y& Elsevier]

Abstract: The determination of trace organophosphonates which are used in cooling towers as a scale inhibitor usually involves extraction and/or concentration of the target components prior to analysis. The extracts are analyzed using chromatographic or spectroscopic methods. This methodology is not only cumbersome but also results in poor data quality. This work presents a novel approach for the rapid and sensitive determination of trace amounts of an organophosphonate: 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP) in aqueous solution. This method is based upon reactive pyrolysis-GC/MS in the presence of tetramethyl ammonium hydroxide (TMAH). Approximately 10μL of the aqueous sample containing a trace amount of HEDP and 1μL of 25% a methanol TMAH solution was placed in the sample cup. The cup was then dropped into the furnace which was at 350°C. The heat initiated the hydrolysis of the organophosphonate followed by the methylation of the hydrolysates. Trimethylphosphate (TMP) was detected by GC/MS. The level of TMP is related to the level of the phosphonate, HEDP in the aqueous sample. Using an external standard calibration curve, it was possible to make a rapid estimation of mg/L levels of organophosphate. [Copyright &y& Elsevier]

Abstract: When a vertical micro-furnace pyrolyzer is adopted for pyrolysis-gas chromatography (Py-GC), the sample is usually introduced into the center of the preheated pyrolysis chamber by mounting it in a small cylindrical sample cup with a dead-end bottom having a volume of a few dozens micro liters which in some case might be responsible for a stagnant flow of carrier gas in the pyrolysis chamber to cause undesirable secondary reactions of the resulting pyrolyzates and/or peak broadening phenomenon. In order to quench the dead-end flow, a new “flow-through” sample cup in which a small hole (ca. 1.0mm i.d.) was drilled through its bottom was developed, and its basic characteristics were first examined by measuring the pyrogram of polycarbonate (PC) at 600°C under different carrier gas flow rates. Various secondary products such as phenol and p-isopropenyl phenol derived from bisphenol A, the main pyrolyzatate of PC were observed when the conventional sample cup without the hole was used under a relatively lower flow rate as 25ml/min. However, they were markedly decreased when the “flow-through” sample cup was used. Furthermore, the resolution of the lower boiling point pyrolyzates (C1–C8) from high density polyethylene (HDPE) was also much improved by use of the “flow-through” sample cup. [Copyright &y& Elsevier]

The structural changes of a polymeric hindered amine light stabilizer (HALS), Adekastab LA-68LD (MW=1900) added in PP materials during UV-irradiation were investigated by reactive thermal desorption-gas chromatography (RTD-GC) in the presence of tetramethylammonium hydroxide [(CH3)4NOH, TMAH]. Not only the products formed from the residual intact HALS, but also those from its oxidized moiety (nitroxyl radical) were observed on the resulting chromatograms without the use of any troublesome sample pretreatment such as solvent extraction. The changes in the yields of these key products were then examined as a function of UV-exposure time. As a result, it was revealed that the amount of the nitroxyl radical increased in the initial stage of UV-irradiation but then slightly decreased mainly because of further decomposition into the smaller compounds, whereas that of the intact HALS monotonously decreased during exposure. [Copyright &y& Elsevier]

Highly sensitive and specific determination of trace amounts of a polymeric hindered amine light stabilizer (HALS) in polypropylene (PP) materials could be established by improving reactive thermal desorption–gas chromatography (RTD–GC) in the presence of an organic alkali, tetramethylammonium hydroxide. By using nitrogen–phosphorus detection, highly selective detection of the HALS-related components was attained. In addition, the use of a polar poly(ethylene glycol) separation column alleviated the adsorption of minor specific pyrolysis products. This modified RTD–GC method allowed the determination of the polymeric HALS (Mr 1900) in PP even for trace concentrations between 100 and 500 ppm, through observing selectively the characteristic products containing a tetramethylpiperidine moiety, which had been impossible to detect under the previous RTD–GC conditions using a non-polar separation column and conventional flame ionization detection. [Copyright &y& Elsevier]

This paper describes a novel measurement technique for in-situ monitoring of the degradation processes of coated C/C composites (carbon fiber-reinforced carbon composites) in combusting fields. The samples tested in this experiment were C/C composites with double coating layers of SiC and glass materials doped with Ca and/or Mg as tracer elements. These samples were exposed in an C2H2/air flame emitted the diatomic molecules, and the light from the Mg–Ca hollow cathode lamp passed through the flame around the sample. The spectrally and spatially resolved images of emission were observed with a spectro CCD camera developed by our group. In this work, two-dimensional atomic absorption spectrometry by using the spectro CCD camera was applied to in-situ monitor the degradation processes of each coating layer and the substrate. The results indicated that the temporal changes in the spatial distribution of atomic absorption caused by Ca and Mg atoms proved to be a good measure for in-situ monitoring of the degradation processes of coated C/C composites in a high temperature flame. [Copyright &y& Elsevier]

Determines the degree of acetylation of chitin and chitosan based on reactive prolysis-gas chromatography (Py-GC), in the presents of an oxalic acid aqueous solution. Evaluation of the degree of acetylation; Observation of values obtained by various methods; Reference to the H NMR method; Indepth look at the Py-GC method. .

Abstract: Thermochemolysis-gas chromatography in the presence of tetrabutylammonium hydroxide was applied to the direct determination of phenolic compounds present as “extractives” in a wood sample (Eucalyptus camaldulensis). The phenolic extractives converted into their perbutyl derivatives were separated from the other phenolic products derived from the lignin skeleton in the observed chromatogram of the wood sample. On the basis of their peak intensities, the contents of the phenolic extractives in the wood sample were rapidly and precisely determined without using preliminary solvent extraction of the wood sample. [Copyright &y& Elsevier]

A highly sensitive method to analyze the intact lipids in a single zooplankter individual at the level of a few tenths of a microgram was developed by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) combined with a direct sampling technique. The sampling procedure involved (1) putting a zooplankter individual sample onto the MALDI sample plate, (2) cutting the sample into a few pieces by means of tweezers, (3) depositing aliquots of matrix and cationization reagent solutions on the zooplankter sample, and (4) irradiating with a N[SUB2] laser to cause MALDI. By using this technique, the mass spectra of the single zooplankter samples showed a series of ions generated from phospholipids with 34 or 36 carbons in the acyl groups and neutral lipids such as triglycerides and diacylglyceryl ethers with 5054 carbons in their acyl and alkenyl groups. Accordingly, this method enabled us to estimate the relative quantity between "structured lipids" (phospholipids) and "storage lipids" (neutral lipids) in an individual zooplankter, which should give us a good clue to elucidate the roles of each class of lipids in its growth. [ABSTRACT FROM AUTHOR]

The enzymatic degradation behavior of poly(ϵ-caprolactone) (PCL) with an α-benzyloxy terminal during an enzymatic degradation test using cholesterol esterase was evaluated complementarily by pyrolysis-gas chromatography (Py-GC) in the presence of tetramethylammonium hydroxide (TMAH) and matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS). On the pyrograms of PCL samples, dimethyl derivative of ϵ-caprolactone and some related products originating from ϵ-caprolactone (ϵ-CL) units were observed together with those from benzyloxy terminal units such as benzyl methyl ether. The relative content of the benzyloxy terminal unit in the residual PCL sample after the degradation test, which was estimated from the relative intensities of the specific pyrolysis, considerably fell down especially in the initial stage of the degradation test. On the other hand, in the MALDI mass spectra, the observed molecular weight distribution of the PCL molecules having a benzyloxy terminal was substantially unchanged during the enzymatic degradation, while PCL molecules without benzyloxy terminal appeared at the lower mass region after the degradation test. These results suggested that the enzymatic degradation of the PCL might proceed mainly in the exo-cleavage mode from α-benzyloxy terminal side under a given condition. [Copyright &y& Elsevier]

Thermally assisted hydrolysis and methylation-gas chromatography (THM-GC) in the presence of trimethylsulfonium hydroxide (TMSH) was applied to the analysis of the lipid contents and their fatty acid compositions in individual zooplankters, especially focusing on polyunsaturated fatty acid (PUFA) components. On the resulting chromatograms, fatty acid components including PUFAs such as eicosapentaenoic acid (EPA; C20:5) and docosahexaenoic acid (DHA; C22:6) in single zooplankters were clearly observed as their methyl esters without doing any tedious and time-consuming pretreatment. By using this technique, the lipid contents and fatty acid compositions in a powdered plankter sample prepared by cryomilling homogenization were estimated on the basis of the observed peak intensities with relative standard deviations of less than 6%. The fatty acid compositions thus determined were in good agreement with those obtained by the conventional technique involving solvent extraction of the samples for every fatty acid component including PUFAs. The differences among individual zooplankter samples were then evaluated by THM-GC method. As a result, the chemical compositions of EPA and DHA showed relatively large inter-individual fluctuations even for the samples cultured under the same conditions. This suggests that lipid biosynthesis of the highly unsaturated fatty acid components and their consumption proceeded differently depending on the life history for each individual zooplankter. [Copyright &y& Elsevier]

A novel rapid and sensitive method to characterize wood extractives in wood samples was developed on the basis of reactive thermal desorption-gas chromatography (RTD-GC) in the presence of an organic alkali, tetramethylammonium acetate ((CH3)4N+OCOCH3−, TMAAc) without using any cumbersome pretreatment such as solvent extraction. The RTD at 200 °C using TMAAc allowed highly sensitive detection of wood extractives such as fatty acid, phenolic acid and gallocatechin components in Eucalyptus camaldulensis as their methyl derivatives on the resulting chromatograms with suppressing the pyrolysis of the major wood constituent to the utmost. The fatty acid contents were able to be determined directly by RTD-GC using approximately 100 μg of the powdered wood samples with in relative standard deviations of 5%. The observed result was in fairly good agreement with that obtained by the conventional standard method including off-line transmethylation of acetone extracts followed by GC measurements. [Copyright &y& Elsevier]

As a novel method for analytical pyrolysis of polymers, pyrolysis-fractography (Py-F) was developed. In this method, the pyrolyzates generated when a polymer is instantaneously pyrolyzed at 600 °C are introduced together with the carrier gas into a short length of deactivated stainless steel capillary tube equipped in the gas chromatographic oven. By a programmed heating the oven temperature is linearly raised, so that the pyrolyzates are fractionated, and a fractogram is obtained using a mass spectrometer or a flame ionization detector. The fundamental study was conducted using polyethylene, and this method was applied to elucidate the pyrolysis behavior of such nitrogen containing polymers as polyurethane and melamine formaldehyde resin. As a result, the Py-F method was proved to be useful in analyzing the pyrolysis behavior of polymeric materials, such as a nitrogen-containing polymer, that generates highly polar components upon pyrolysis. [Copyright &y& Elsevier]

Reactive pyrolysis-gas chromatography (Py-GC) in the presence of oxalic acid was applied to the determination of degree of substitution (DS) in N-carboxyethylated chitin derivatives. On the obtained pyrogram, characteristic products, such as methylacrylate, ethylacrylate and acrylic acid originating from the carboxyethyl branches of the chitin derivatives, were clearly observed together with those from the N-acetyl-d-glucosamine units, such as acetonitrile, acetic acid and acetamide. On the basis of relative yields of these characteristic products, the DS values were precisely evaluated. The results by reactive Py-GC also supported the validity of the results obtained by 1H NMR that the mono-alkylation onto the amino group of the original chitin was favorable for the derivatization of the samples. [Copyright &y& Elsevier]

Compositional analysis of UV-cured resins consisting of multi-component acrylic esters was studied by pyrolysis–gas chromatography (Py–GC) in the presence of organic alkali, tetramethylammonium hydroxide (TMAH). The pyrograms of the UV-cured resins formed from ethylene oxide modified bisphenol A diacrylate (EBADA) contained specific products such as methyl acrylate (MA) and various dimethyl ethers of ethylene oxide modified bisphenol A reflecting the numbers of ethylene oxide units in the original EBADA. Meanwhile the pyrograms of the UV-cured resins comprised of acrylated polyfunctional aliphatic alcohols such as pentaerythritol triacrylate (PETA) and dipentaerythritol hexacrylate (DPEHA) contained methyl ethers reflecting the structure of the original alcohols. In addition, considerable amounts of pyrolyzates with non-methylated hydroxyl groups were also detected for aliphatic alcohol moieties. The compositions of the UV-cured resins containing multi-component acrylic esters were also analyzed based on the relative yields of the characteristic pyrolyzates of each acrylic ester. For calibration purpose, a series of UV-cured standard samples, which contained known amounts of the individual acrylic ester and neopentylglycol diacrylate (NPGDA) used as an internal standard, were measured. The compositions of the multi-component UV-cured resins determined using this approach showed good agreement with the theoretical values estimated from the feed composition. [Copyright &y& Elsevier]

Presents a quantitative analysis of detailed lignin monomer composition by pyrolysis-gas chromatography. Contribution of the lignin acetylation procedure; Determination of the dehydrogenative polymers; Accuracy of the preacetylation in analyzing the detailed lignin monomer composition.

A novel solid-phase extraction element is developed for sorptive enrichment of dilute analytes from liquid samples with high extraction efficiencies due to its larger amounts of polydimethylsiloxane (PDMS) absorbent than the conventional syringe type of solid-phase microextraction (SPME). The extraction element is made of titanium (Ti) open tubular tube (30 mm×1.2 mm i.d.×1.6 mm o.d.) coated with a chemically bonded layer of PDMS (500 μm in thickness). The extraction element combined with thermal desorption–gas chromatography–mass spectrometry using a pyrolysis–gas chromatography–mass spectrometry system was used to extract and analyze a typical herbicide, bethrodine in water samples over a concentration range from 2.5 to 2.5×104 ng/l. Thus obtained calibration curve showed good linearity for the tested whole concentration range with regression coefficient of 0.992. Detection limit of 0.5 ng/l level was achieved and the reproducibility of the measurements for bethrodine at 10 ng/l level was found to be fairly good with relative standard deviation below 7.5%. [Copyright &y& Elsevier]