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Abstract: Reaction efficiencies of two organic alkalis, tetramethylammonium hydroxide (TMAH) and trimethylsulfonium hydroxide (TMSH), with lipids during thermally assisted hydrolysis and methylation (THM) were examined focusing on (1) the types of lipids and (2) degree of unsaturation of fatty acid moieties. Different types of lipids such as triglycerides, phospholipids, free fatty acids and cholesteryl esters containing saturated, monounsaturated or polyunsaturated fatty acid (PUFA) residues were subjected to THM-gas chromatography (GC) in the presence of TMAH or TMSH. The obtained results revealed that the THM reaction using TMAH allowed almost quantitative methylation of saturated and monounsaturated fatty acid components independently of the classes of lipids. However, strong alkalinity of TMAH brought about isomerization and/or degradation of PUFA components. In contrast, the use of TMSH was effective to highly sensitive detection of PUFA as well as saturated and monounsaturated fatty acid components contained in triglycerides, phospholipids (phosphatidylcholines) and free fatty acids. On the other hand, TMSH was proved to react hardly with any kind of fatty acid residues in cholesteryl esters due to their steric hindrance. [Copyright &y& Elsevier]

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]

Discusses the characterization of natural resin shellac by reactive pyrolysis-gas chromatography in the presence of organic alkali, tetramethylammonium hydroxide. Determination of terpenic acids, aleuritic acid, several minor fatty acids and wax components of shellac; Distribution of acidic components for shellac samples produced in India and Thailand.

Determines styrene copolymer sizing agents in paper by pyrolysis gas chromatography. Use of styrene monomer derived from the styrene sequences; Determination of the amounts of sizing agents retained in paper samples; Interpretation of the amounts of sizing agents in paper by degree of sizing.

There is considerable interest in the development of simple methods for quantifying production of the biodegradable polyester poly(3-hydroxybutyrate) [P(3HB)] by bacteria. Cells of Cupriavidus necator were grown on agar medium containing different concentrations of glucose (10–25 g/L) as a sole carbon source. Trace amounts (100±5 μg) of dried C. necator cells were directly subjected to thermally assisted hydrolysis and methylation-gas chromatography (THM-GC) in the presence of tetramethylammonium hydroxide (TMAH). On the resulting chromatograms, a series of characteristic peaks, attributed to the THM products from poly(3-hydroxybutylate) accumulated in the bacterial cells, were clearly observed without any interfering component. Based on the peak intensities, the contents of P(3HB) in C. necator were determined precisely and rapidly without using any cumbersome sample pretreatment. Furthermore, the values of the P(3HB) contents coincided overall with those obtained by the conventional method involving solvent extraction followed by gravimetric determination. [ABSTRACT FROM AUTHOR]

Highlights • THM-GC was applied to monitor the change in copolymer composition of film samples during soil burial test. • 3 HHx moieties in the polymer chains were preferentially biodegraded owing to their low crystallinity. • Local variation in the degree of biodegradation using only 30 μg of P(3HB-co-3HHx) film sample. Abstract Soil burial biodegradation behavior of poly(3-hydroxybutyrate- co -3-hydroxyhexanoate) [P(3HB- co -3HHx)] was studied based on its copolymer composition determined by thermally assisted hydrolysis and methylation-gas chromatography (THM-GC). The change in copolymer composition of P(3HB- co -3HHx) film samples during soil burial degradation test was monitored in detail by THM-GC. As a result, the copolymer compositions of 3HB units gradually increased, while those of 3HHx units decreased with soil burial time, almost correlating with recovery weight. Based on these results, the biodegradation mechanism of P(3HB- co -3HHx) was elucidated with considering the influence of the crystallinity on the biodegradability. Furthermore, local differences in biodegradability of a given P(3HB- co -3HHx) film after soil burial test were also successfully evaluated from the copolymer compositions obtained by THM-GC. [ABSTRACT FROM AUTHOR]

Thermally assisted hydrolysis and methylation-gas chromatography (THM-GC) in the presence of an organic alkali was validated for the compositional analysis of poly(3-hydroxybutyrate- co -3-hydroxyhexanoate) [P(3HB- co -3HHx)] accumulated in whole bacterial cells. Recombinant Cupriavidus necator Re2058/pCB113 was grown in a batch fermentation with different concentration of palm oil and fructose in order to control the molar fraction of 3HHx in P(3HB- co -3HHx) produced in the cells. Trace amounts (30 μg) of freeze-dried cells were directly subjected to THM-GC in the presence of tetramethylammonium hydroxide (TMAH) at 400 °C. The obtained chromatograms clearly showed nine characteristic peaks, attributed to the THM products from 3HB and 3HHx units in the polymer chains, without any appreciable interference by the bacterial matrix components. Based on these peak intensities, the copolymer compositions were determined rapidly without using any cumbersome and lengthy sample pretreatment as in conventional GC method. Moreover, the compositions thus obtained were strongly correlated with those by NMR and conventional GC involving solvent extraction. [ABSTRACT FROM AUTHOR]

Biodegradability of poly(butylene succinate-co-butylene adipate) (PBSA) was studied based on its copolymer composition determined by thermally assisted hydrolysis and methylation-gas chromatography (THM-GC) using trace amounts (20 µg) of the film samples. The copolymer compositions of butylene adipate (BA) units gradually decreased with soil burial degradation time, reflecting preferential biodegradation of BA moieties during soil burial due to their lower crystallinity. Furthermore, local differences in biodegradability of a given PBSA film after soil burial were also successfully evaluated. [ABSTRACT FROM PUBLISHER]

Abstract: Conventional methods used to analyze total fatty acids in wood generally require tedious and time-consuming pretreatments such as solvent extraction and hydrolysis of esterified fatty acids of fats. In this study, both total fatty acid composition and the yield from free and esterified fatty acids of fats in Acacia species were investigated using a rapid and direct method of thermochemolysis–gas chromatography (GC)–flame ionization detector (FID)/mass spectrometry (MS) with organic alkalis. Using tetrabutylammonium hydroxide (TBAH) at 300°C, thermochemolysis–GC–FID/MS gave total fatty acids including the fat origin as pyrolyzates with suppressed lignin fragment formation because of the basicity of TBAH compared to other organic alkalis: tetramethylammonium hydroxide and tetramethylammonium acetate. The obtained results of fatty acid composition were consistent with those obtained using conventional methods consisting of a series of procedures such as solvent extraction, hydrolysis, derivatization, and analysis by GC–FID/MS in fatty acid composition analysis. Furthermore, thermochemolysis–GC–FID gave a higher yield of total fatty acid than the conventional method, quantitatively reflecting the difficulty in solvent extraction of these components. Consequently, thermochemolysis–GC with TBAH promises to be a rapid and direct method to characterize total fatty acids in wood, avoiding artifacts by solvent extraction of wood. Furthermore, this method discriminated Acacia auriculiformis from Acacia mangium based on the observed fatty acid contents and selected individuals containing low total fatty acids to minimize paper sliding on a printer drum. [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]

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]

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.