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PubMed2000

Polymer additive analysis by pyrolysis-gas chromatography. I. Plasticizers.

Plasticizers are widely used in thermoplastic polymers to modify their physical properties and processibility. Plasticizers as well as most of the other additives in the polymer can be qualitatively analyzed by pyrolysis-gas chromatography (Py-GC) simultaneously with the polymer composition. The key to the successful analysis of plasticizers not only requires a comprehensive understanding of commercial plasticizers but also requires knowledge of the polymer and its applications, as well as the Py-GC technique. In this study, several plasticizers in different polymeric systems were studied to demonstrate the utility of Py-GC as a good tool for the characterization of these systems. The advantages of using Py-GC for plasticizer analysis are also discussed.

Chromatography, Gas↗
PubMed2000

Qualitative and quantitative analysis of a thermoset polymer, poly(benzoxazine), by pyrolysis-gas chromatography.

The chemical composition of a poly(benzoxazine) thermoset polymer (a copolymer of bisphenol-A benzoxazine and tert.-butylphenol benzoxazine) has been studied by pyrolysis-gas chromatography (Py-GC). Major pyrolysates have been identified and the possible degradation pathways have been investigated. A specific pyrolysate was identified for quantitative analysis after carefully proving the linear relationship between the pyrolysate signal intensity and monomer concentration over a wide range of compositions. A method to determine the concentration of the monomer that potentially acts as a cross-linking unit has been developed. In this study, Py-GC was shown to be an excellent analytical technique for the qualitative and quantitative analysis of thermoset polymers.

Gas Chromatography-Mass Spectrometry↗
PubMed2000

Polymer additive analysis by pyrolysis-gas chromatography. II. Flame retardants.

Flame retardants are widely used in thermoplastic polymers for household and transportation applications. Flame retardants as well as most of the other additives in the polymer can be qualitatively analyzed by pyrolysis-gas chromatography (Py-GC) simultaneously with the polymer composition. The key to successful analysis of flame retardants not only requires a thorough knowledge of the various types of flame retardants but also necessitates an understanding of the parent polymer and its targeted applications. In this study, several flame retardants in different polymer matrices have been studied to demonstrate the utility of Py-GC for the analysis of flame retardants. The advantages of Py-GC for flame retardants analysis have also been discussed.

Chromatography, Gas↗
PubMed2000

Number-average molecular mass determination of polymeric material by pyrolysis-gas chromatography.

The number-average molecular mass of a polymeric material has been determined by pyrolysis-gas chromatography (Py-GC) via end-group analysis. The major advantage of this technique is that no sample preparation is required. The sample is not required to be in the dilute solution form, and the amount of sample needed is approximately 0.5 mg. Phenyl group-terminated polybutadiene systems have been studied as an example. The application of Py-GC to obtain the end-group concentration, the number-average molecular mass and the limitations of this method are discussed in detail. The success of this development elevates the role of Py-GC as an important technique for end-group analysis for the determination of number-average molecular mass.

Chromatography, Gas↗
PubMed2000

Polymer additive analysis by pyrolysis-gas chromatography. IV. Antioxidants.

Antioxidants are important additives in polymers. Because of the low level of antioxidants normally used, they cannot be analyzed directly by common spectroscopic or thermal chemical techniques. However, antioxidants as well as other additives in polymers can be qualitatively analyzed by pyrolysis-gas chromatography (Py-GC) after separating the polymers and additives. In this study, several antioxidants have been investigated to demonstrate that Py-GC is a viable tool to analyze them. The advantages of using Py-GC in the analysis of antioxidants have also been discussed.

Antioxidants↗
PubMed2000

Polymer additive analysis by pyrolysis-gas chromatography. III. Lubricants.

Lubricants are widely used in thermoplastic polymers to increase the overall rate of processing or to improve surface release properties. Because of the low level of lubricants normally used in a polymer, it may not be possible to analyze the additive directly by common spectroscopic or thermal chemical techniques. However, lubricants as well as other additives in the polymer can be qualitatively analyzed by pyrolysis-gas chromatography (Py-GC) after extraction. In this work, several lubricants have been studied to demonstrate that Py-GC is a viable tool to investigate lubricants. The advantages of using Py-GC in the analysis of lubricant have also been discussed.

Chromatography, Gas↗
PubMed2000

Analysis of phenols in pyrolysis oils by gel permeation chromatography and multidimensional liquid chromatography.

A simple method with minimal manual sample preparation was developed for the analysis of phenols in pyrolysis oils. Sample pre-treatment was done by gel permeation chromatography (GPC), where the high-molecular-mass lignins were separated from the phenols. Multidimensional liquid chromatography (LC-LC) was used in the analysis of the phenolic fraction. The pre-column was used for sample clean-up and pre-fractionation before introduction of the phenolic fraction to the analytical column. The repeatability and linearity of the total GPC and LC-LC methods were excellent. The results were in accordance with the reference method in which the sample pre-treatment was done by precipitating the lignins with water, and the phenols were extracted with toluene and analysed by GC-MS.

Chromatography, Gel↗
PubMed1975

Use of combined chromatographic methods including thin-layer chromatography for analysis of complex polymer systems. Determination of the polydispersity of block copolymers of styrene and methyl methacrylate by gel permeation, thin-layer and pyrolysis gas chromatography.

A combination of gel permeation chromatography (GPC), thin-layer chromatography (TLC) and pyrolysis gas chromatography (PGC) has been used for investigations of a polymethyl methacrylate-polystyrene-polymethyl methacrylate block copolymer. Continuous distribution of the polymer (40-mg sample) was attained according to the content of the styrene and methyl methacrylate units and of the block copolymer and according to the composition of the copolymer as functions of the hydrodynamic radius of the macromolecules. The polymer was subjected to a preliminary fractionation with an analytical gel chromatograph. The fractions were investigated by TLC, which permitted the separation of the block copolymer and the homopolymers. The composition of the fractions obtained by GPC and TLC was determined by PGC. As a result, it was possible to establish the composition of the block copolymer and its ratio to polymethyl methacrylate in each fraction. This investigation was based on a combination of highly effective fractionation by chromatographic methods with precise quantitative ratios obtained from Benoit's universal calibration graph and from determinations of the composition of the polymer fractions by PGC. The mechanism of the TLC of polymers, including the appearance of artefacts that distort the results of analysis, is also discussed.

Chromatography↗
PubMed1979

Classification of fungi by means of pyrolysis-gas chromatography-pattern recognition.

Repetitive samples of three strains of the mould Penicillium were subjected to pyrolysis-gas chromatography (Py-GC). From the chromatograms, 26 peak heights were used in a subsequent SIMCA pattern recognition analysis. This data analysis gives a marked improvement in the classification of the samples (100% correct, 85% unique) in comparison with the traditional analysis based on the average chromatogram of each class (92% correct, 45% unique). The data analytical method is described in detail using the Py-GC data as an illustration.

Analysis of Variance↗
PubMed1989

Pyrolysis gas-liquid chromatography of N,N-dimethylalkylamine N-oxides and their mixtures.

A rapid quantitative and small scale method based on direct injection pyrolysis gas-liquid chromatography is described for the determination of N,N-dimethylalkylamine N-oxides. The method is suitable for determination of individual N-oxides as well as of their homologous compositions with or without the presence of parent tertiary amines in water or methanol solutions. The sensitivity of the method is 10-15 nmol of compounds injected. The unsymmetrical (1-methyldodecyl)dimethylamine N-oxide forms two isomeric alkenes 1-tridecene and trans-2-tridecene in a ratio of 1.68, in agreement with the predicted value.

Chromatography, Gas↗
PubMed1990

Application of pyrolysis-high-resolution gas chromatography-pattern recognition to the identification of the Chinese traditional medicine mai dong.

Pyrolysis-high-resolution gas chromatography-pattern recognition (Py-HRGC-PaRe) was used to develop a potential technique for identifying the Chinese traditional medicine Mai Dong. About 1 mg of crude drug powder was pyrolysed in a furnace pyrolyser and the products were directly carried into a gas chromatograph with an FSOT capillary column (30 m x 0.265 mm I.D.) coated with DB-1701 (df 0.25 micron). The Py-HRGC data were analysed by non-linear mapping PaRe. The results showed that Mai Dong samples could be classified into two categories: Ophiopogon japonicus (L.f.) Ker-Gawl (included in the Chinese Pharmacopoeia) and Liriope spicata.

Chromatography, Gas↗
PubMed1987

Characterization of biopolymers by pyrolysis gas chromatography and multidimensional analysis. Application to synthetic melanins.

A method for characterization of the melanin biopolymer has been developed and validated by the use of synthetic melanins derived from tyrosine, dopamine or hydroquinone. The technique involved pyrolysis gas-liquid chromatography with capillary columns. A back-flushing technique is described which improves pyrogram reproducibility such that closely related melanins can be distinguished with the aid of principal components analysis and non-metric multidimensional scaling.

Biopolymers↗
PubMed2003

Determination of aromatic primary amines at microg l(-1) level in environmental waters by gas chromatography-mass spectrometry involving N-allyl-n'-arylthiourea formation and their on-line pyrolysis to aryl isothiocyanates.

Derivatization of aromatic primary amines to N-allyl-N'-arylthioureas by reaction with allyl isothiocyanate and GC-MS of the derivatives, when pyrolysis to aryl isothiocyanates occurs in the heated injector, has been used to determine aromatic amines in the range 0.5-50 microg l(-1) with a correlation coefficient, r, in the range 0.9902-0.9992. The limit of detection ranged 8 to 30 ng l(-1) when 60 ml of sample were preconcentrated, after derivatization, on a styrene-divinylbenzene copolymer sorbent. The pyrolytic cleavage of sym- and unsym-diaryl or alkyl-/arylthioureas has been rationalized. The chromatography of isothiocyanates is much superior to that of aryl amines and the specific mass fragmentation permits positive identification of amines. The method has been applied to spiked drinking water, groundwater and river water samples, when the recovery ranged from 84 to 109% with RSD of 5-9%, and to detect aromatic amines formed by reductive cleavage of azo dyes in effluents when the recovery of amine was in the range 81-95% with RSD 8-15%. The method is not applicable to nitroanilines.

Amines↗
PubMed1999

Pyrolysis-gas-liquid chromatography with atomic emission detection for the identification of Corynebacterium species.

We report here the application of pyrolysis-gas chromatography followed by atomic emission detection (AED) for the characterisation of microorganisms. AED measured the quantity of carbon, sulfur and nitrogen in the molecules separated chromatographically. Twenty-three strains, representing eight Corynebacterium species, were tested in this preliminary study. Co-ordinate principal analysis grouped 11 strains in their respective species group. Most of the other strains appear randomly distributed, perhaps because these strains require additional nutrients. These preliminary results show that the method could be used as a tool for the taxonomic and perhaps the epidemiologic characterisation of bacteria.

Carbon↗
PubMedDate not supplied

Characterization of biomass pyrolysis vapors with molecular beam, single photon ionization time-of-flight mass spectrometry.

A single photon ionization, molecular beam sampling, reflectron time-of-flight mass spectrometer (SPI/MBTOFMS) has been developed and used to study pyrolysis products from a selection of biomass materials. Spectra are characterized by high resolution and decreased fragmentation compared to electron-impact ionization mass spectra from related molecular beam mass spectrometer systems equipped with quadrupole mass analyzers.

Biomass↗