Open Access

Die Kombination der analytischen Pyrolyse mit der Gaschromatographie-Massenspektrometrie erweitert die Möglichkeiten, die strukturellen Eigenschaften polymerer Materialien zu untersuchen und zu charakterisieren.

A method for the identification of volatile organic compounds (VOCs) released from packaging expanded polystyrene (EPS) is presented. Headspace solid-phase microextraction (HS-SPME) with a 75-μm carboxen-polydimethylsiloxan fiber was used as sample preparation technique before the determination of the volatile organic compounds by gas chromatography–mass spectrometry (GC-MS). For separation of compounds, two fused silica capillary columns of different polarity (DB-5ms and BPX-50) were used. Styrene monomer with his impurities and oxidation products, as well as residual pentane, were identified in the headspace of EPS.

A method for determination of residual styrene monomer and other volatile organic compounds in expanded polystyrene (EPS) was developed using HS SPME and gas chromatography with FID. The extraction products were identified by GC/MS. Good reproducibility of the measurements with RSD values between 3.2–3.6% was achieved by extraction using a 75 ?m Carboxen-Polydimethylsiloxane fiber at 60°C with 15 min sample sonication. The contents of residual styrene monomer in two samples of EPS were 153.2 and 65.7 mg/kg, respectively. Other compounds identified in EPS were pentane, benzene, toluene, ethylbenzene, isomers of xylene, n-propylbenzene, 1,2,4-trimethylbenzene, o-methylstyrene, benzaldehyde, benzyl alcohol, and acetophenone.

The analytical pyrolysis technique hyphenated to gas chromatography–mass spectrometry (GC–MS) has extended the range of possible tools for the characterization of synthetic polymers and copolymers. Pyrolysis involves thermal fragmentation of the analytical sample at temperatures of 500–1400 °C. In the presence of an inert gas, reproducible decomposition products characteristic for the original polymer or copolymer sample are formed. The pyrolysis products are chromatographically separated using a fused-silica capillary column and are subsequently identified by interpretation of the obtained mass spectra or by using mass spectra libraries. The analytical technique eliminates the need for pretreatment by performing analyses directly on the solid or liquid polymer sample. In this article, application examples of analytical pyrolysis hyphenated to GC–MS for the identification of different polymeric materials in the plastic and automotive industry, dentistry, and occupational safety are demonstrated. For the first time, results of identification of commercial light-curing dental filling material and a car wrapping foil by pyrolysis–GC–MS are presented.

Gas chromatography with flame-ionization detection (FID) and gas chromatography-mass spectrometry (GC/MS) with electron impact ionization (EI) and chemical ionization (PCI and NCI) were successfully used for separation and identification of commercially available longchain primary alkyl amines. The investigated compounds were used as corrosion inhibiting and antifouling agents in a water-steam circuit of energy systems in the power industry. Solidphase extraction (SPE) with octadecyl bonded silica (C18) sorbents followed by gas chromatography were used for quantification of the investigated Primene JM-T™ alkyl amines in boiler water, condensate and superheated steam samples from the power plant. Amine formulations from Kotamina group favor formation of protective layers on internal surfaces and keep them free from corrosion and scale. Alkyl amines contained in those formulations both render the environment alkaline and limit the corrosion impact of ionic and gaseous impurities by formation of protective layers. Moreover, alkyl amines limit scaling on heating surfaces of boilers and in turbine, ensuring failure-free operation. Application of alkyl amine formulation enhances heat exchange during boiling and condensation processes. Alkyl amines with branched structure are more thermally stable than linear alkyl amines, exhibit better adsorption and effectiveness of surface shielding. As a result, application of thermostable long-chain branched alkyl amines increases the efficiency of anti-corrosive protection. Moreover, the concentration of ammonia content in water and in steam was also considerably decreased.

Der zunehmende Einsatz der Polymerwerkstoffe in der Automobilindustrie erfordert empfindliche und zuverlässige Methoden zur Analyse der verwendeten Stoffe. Bei Schadenanalysen an Komponenten in Kraftfahrzeugen stehen oftmals nur wenige Informationen über das Bauteil selbst, wie die chemische Zusammensetzung, die Temperaturbeständigkeit, mögliche Kontaminierungs stoffe oder mechanische Eigenschaften zur Verfügung. Der Schadensbereich ist meistens be grenzt und nicht immer homogen. Zur Klärung des Schadens stehen häufig nur kleine Proben mengen zur Verfügung, die jedoch für die Erkennung der Schadensursache von großer Bedeutung sein können.

Anwendung der Pyrolyse-GC/MS in der Schadensanalyse verschiedener Kunststoff- oder Metallbauteile aus der Automobilindustrie.

For failure analysis, there often is a lack of information about the component itself, such as chemical composition, temperature resistance, possible contaminants, or mechanical properties. The damage range usually is limited and not always homogeneous. Very often, only small amounts of samples are available, which may be important for recognizing the cause of damage. Traditional analytical techniques used for characterization of high molecular weight organic compounds, such as thermal analysis and Fourier transform infrared spectroscopy (FTIR), have limitations or are not sufficiently sensitive to demonstrate the change of the structure and the resulting dysfunction of used materials. The analytical pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) has extended the range of possible tools for the characterization of synthetic polymers/copolymers or rubbers in failure analysis in various industrial fields of application, predominantly in the automotive industry.