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Mass Spectrometry: Pyrolysis
(2017)
Pyrolysis mass spectrometry (PyMS) is a sensitive analytical technique in which samples are subjected to rapid thermal degradation (pyrolysis) before the derivative ions are separated in a mass spectrometer. The technique is particularly suitable for the analysis of otherwise nonvolatile compounds in complex samples. The masses of pyrolyzate are expressed as a pyrolysis mass spectrum. This can be interpreted and used to characterize the structures of the parent molecules in the sample, or used in an uninterpreted manner to provide a diagnostic fingerprint that can easily distinguish between related complex samples, such as different microbial strains.
The article describes the development of pyrolysis mass spectrometry and its history, the state of the art, instrumentation and applications for the identification of high molecular organic compounds by using of multivariate analysis and supervised learning methods.
Gas chromatography with flame-ionization detection (FID) and gas chromatography-mass spectrometry (GC/MS) has been used for structure elucidation of long-chain primary n-alkyl amines after derivatization with trifluoroacetic anhydride (TFAA). Electron impact ionization- (EI) and positive chemical ionization- (PCI) mass spectra of trifluoroacetylated derivatives of the identified nalkyl amines are presented. The corrosion inhibiting n-alkyl amines were applied in the investigation of a new anticorrosive and antifouling formulation for water-steam circuit of energy systems in the power industry. The presented results are part of an EU-funded international collaboration with partners from research institutes and industry from Poland, Lithuania, Romania, France and Germany (EUREKA project BOILTREAT E!2426).
This paper describes the application examples of gas chromatography/mass spectrometry (GC/MS) and pyrolysis–gas chromatography/mass spectrometry (Py-GC/MS) in failure analysis for the identification of chemical materials like mineral oil from a malfunctioning motorbike and a complaint car tire rubber. Furthermore, failure case demanding identification of chemical composition of solid plastic particles from a failed mechanical engineering component is demonstrated. The obtained analytical results were then used for troubleshooting and remedial action of the technological processes.
Headspace-SPME-GC-MS identification of volatile organic compounds released from expanded polystyrene
(2004)
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.
The criteria for assessing the quality of rubber materials are the polymer or copolymer composition and the additives. These additives include plasticizers, extender oils, carbon black, inorganic fillers, antioxidants, heat and light stabilizers, processing aids, cross-linking agents, accelerators, retarders, adhesives, pigments, smoke and flame retardants, and others. Determination of additives in polymers or copolymers generally requires the extraction of these substances from the matrix as a first step, which can be challenging, and the subsequent analysis of the extracted additives by gas chromatography (GC), GC–mass spectrometry (MS), high performance liquid chromatography (HPLC), HPLC–MS, capillary electrophoresis, thin-layer chromatography, and other analytical techniques. In the present work, nitrile rubber materials were studied using direct analytical flash pyrolysis hyphenated to GC and electrospray ionization MS in both scan and selected ion monitoring modes to demonstrate that this technique is a good tool to identify the organic additives in nitrile rubber.
A simple reversed-phase high-performance thin-layer chromatographic (HPTLC) method for the identification and quantitative determination of caffeine in Coca-Cola is described. The chromatographic conditions of the HPTLC method are further adapted by developing the HPLC method for identification and determination of caffeine in cola drinks and other caffeine-containing beverages. The results of the quantitative determinations of caffeine in Coca-Cola obtained by using both HPTLC and HPLC methods were 96.1 ± 1.1 mg L–1 and 95.4 ± 0.2 mg L–1, respectively. The experimental objective for the students is to determine the unknown amount of caffeine in a complex matrix by two different chromatographic techniques. The pedagogical objective is to make students familiar with these well-established techniques. Furthermore, they learn about the usefulness, difficulties, and limitations of comparative analytical studies. The two-part experiment has been developed for second-year chemistry and biology undergraduate students and is performed in the instrumental analysis course in two three-hour laboratory sessions.
An experiment for identification of flavor components in Original Eau de Cologne by headspace solid-phase microextraction (HS-SPME) followed by gas chromatography-mass spectrometry (GC-MS) with electron impact ionization was developed. A new SPME fiber with a dual coating of divinylbenzene and Carboxen, each suspended in polydimethylsiloxane, was used. The compounds were identified by search of the NIST 98 MS Library or by comparison with pure standards. The experiment was developed for second-year chemistry students to learn the principles of analytical instrumentation (GC-MS) and sample preparation techniques (HS-SPME). The students are able to complete this experiment in a single four-hour laboratory session.
Analysis of Synthetic Polymers and Copolymers by Pyrolysis- Gas Chromatography/Mass Spectrometry
(2005)
Structural analysis and the study of degradation properties are important in order to understand and improve performance characteristics of synthetic polymers and copolymers in many industrial applications. Polymers/copolymers are inherently difficult to analyze because of their high molecular weight and lack of volatility. Traditionally, various analytical techniques are used to characterize polymers/copolymers including physical testing (rheological testing), thermogravimetric analysis (TGA), electron microscopy, Fourier transform infrared (FTIR) spectroscopy, size-exclusion chromatography (SEC)/gel permeation chromatography (GPC), and mass spectrometry (MS). Often, time consuming sample preparation, including hydrolysis, dissolution, or derivatization is needed before analysis.
Gas chromatography with simultaneous flame-ionization detection (FID) and a nitrogen-phosphorus detection (NPD) as well as gas chromatography-mass spectrometry (GC/MS) has been used to characterize long-chain primary alkyl amines after derivatization with trifluoroacetic anhydride (TFAA). Electron impact ionization- (EI) and negative chemical ionization (NCI) mass spectra of trifluoroacetylated derivatives of the identified tert-octadecylamines are presented for the first time. The corrosion inhibiting alkyl amines were applied in a water-steam circuit of energy systems in the power industry. Solid-phase extraction (SPE) with octadecyl bonded silica (C18) sorbents followed by gas chromatography were used for quantification of the investigated tert-octadecylamines in boiler water, superheated steam and condensate samples from the power plant. The estimated values were: 89 microg l(-1)(n = 5, RSD = 7.8%), 45 microg l(-1) (n = 5, RSD = 5.4%) and 37 microg l(-1)(n = 5, RSD = 2.3%), respectively.
Refers To: Peter Kusch, Gerd Knupp, Marcus Hergarten, Marian Kozupa, Maria Majchrzak: Solid-phase extraction-gas chromatography and solid-phase extraction-gas chromatography–mass spectrometry determination of corrosion inhibiting long-chain primary alkyl amines in chemical treatment of boiler water in water-steam systems of power plants. - Journal of Chromatography A, Volume 1113, Issues 1–2, 28 April 2006, Pages 198-205
Gas chromatography–mass spectrometry has been used to identify long-chain (C8–C18) N-1-alkyl-1,3-propanediamines after derivatization with trifluoroacetic anhydride. Electron impact ionization and negative chemical ionization mass spectra of trifluoroacetylated derivatives of the identified N-1-alkyl-1,3-propanediamines are presented for the first time. The corrosion inhibiting long-chain N-1-alkyl-1,3-propanediamines were applied in the preparation and investigation of a new anticorrosive and antifouling formulation for water–steam circuit of energy systems in the power industry. Using the GC–MS data, it was possible to identify residues of the N-1-alkyl-1,3-propanediamines in complex samples of boiler water from the power plant after solid-phase extraction and acylation.
The criteria for assessing the quality of rubber materials are the polymer or copolymer composition and the additives. These additives include plasticizers, extender oils, carbon black, inorganic fillers, antioxidants, heat and light stabilizers, processing aids, cross-linking agents, accelerators, retarders, adhesives, pigments, smoke and flame retardants, and others. Determination of additives in polymers or copolymers generally requires the extraction of these substances from the matrix as a first step, which can be challenging, and the subsequent analysis of the extracted additives by gas chromatography (GC), GC-mass spectrometry (MS), high performance liquid chromatography (HPLC), HPLC-MS, capillary electrophoresis, thin-layer chromatography, and other analytical techniques. In the present work, nitrile rubber materials were studied using direct analytical flash pyrolysis hyphenated to GC and electrospray ionization MS in both scan and selected ion monitoring modes to demonstrate that this technique is a good tool to identify the organic additives in nitrile rubber.
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.
An experiment for the identification of synthetic polymers and copolymers by analytical pyrolysis–gas chromatography/mass spectrometry (Py–GC/MS) was developed and performed in the polymer analysis courses for third-year undergraduate students of chemistry with material sciences, and for first-year postgraduate students of polymer sciences. In order to illustrate this analytical technique, polystyrene (PS) and poly(acrylonitrile-co-1,3-butadiene-co-styrene) (ABS) were selected for identification. The students were able to complete this experiment in a single 6 h (a 45 min) or in two 3 h (a 45 min) laboratory sessions. The success rate in the determining of PS was 100%. Because the task of identifying ABS is more demanding, the success rate was about 80–90%. Successful completion of the laboratory experiments and a laboratory report are required of students to obtain a permit for the examination in the polymer analysis course.
Pyrolysis–Gas Chromatography
(2018)
The methodology of analytical pyrolysis-GC/MS has been known for several years, but is seldom used in research laboratories and process control in the chemical industry. This is due to the relative difficulty of interpreting the identified pyrolysis products as well as the variety of them. This book contains full identification of several classes of polymers/copolymers and biopolymers that can be very helpful to the user. In addition, the practical applications can encourage analytical chemists and engineers to use the techniques explored in this volume.
The structure and the functions of various types of pyrolyzers and the results of the pyrolysis–gas chromatographic–mass spectrometric identification of synthetic polymers/copolymers and biopolymers at 700°C are described. Practical applications of these techniques are also included, detailing the analysis of microplastics, failure analysis in the automotive industry and solutions for technological problems.
In searching for new targets for antimalarials we investigated the biosynthesis of hypusine present in eukaryotic initiation factor-5A (eIF-5A) in Plasmodium. Here, we describe the cloning and expression of deoxyhypusine hydroxylase (DOHH), which completes the modi. cation of eIF-5A through hydroxylation of deoxyhypusine. The dohh cDNA sequence revealed an ORF of 1236 bp encoding a protein of 412 amino acids with a calculated molecular mass of 46.45 kDa and an isoelectric point of 4.96. Interestingly, DOHH from Plasmodium has a FASTA SCORE of only 27 compared with its human ortholog and contains several matches similar to E-Z-type HEAT-like repeat proteins (IPR004155 (InterPro), PF03130 (Pfam), SM00567 (SMART) present in the phycocyanin lyase subunits of cyanobacteria. Purified DOHH protein displayed hydroxylase activity in a novel in vitro DOHH assay, but phycocyanin lyase activity was absent. dohh is present as a single-copy gene and is transcribed in the asexual blood stages of the parasite. A signal peptide at the N-terminus might direct the protein to a different cellular compartment. During evolution, Plasmodium falciparum acquired an apicoplast that lost its photosynthetic function. It is possible that plasmodial DOHH arose from an E/F-type phycobilin lyase that gained a new role in hydroxylation.
Die analytische Pyrolyse ist eine universell einsetzbare Messtechnik zur Untersuchung von hoch molekularen organischen Verbindungen. Bei der Pyrolyse der hochmolekularen organischen Ver bindungen entstehen durch thermische Zersetzung bei 500-1400°C in einem Inertgasstrom nieder molekulare Verbindungen. Diese niedermolekularen Pyrolyse-Produkte werden dann den her kömmlichen Analyseverfahren wie GC-FID, GC/MS oder GC/FTIR unterworfen, die Rück schlüsse auf chemische Zusammensetzung und Struktur der Ausgangsstoffe erlauben. Die Festphasen mikroextraktion (SPME) ist eine lösungsmittelfreie Mikroextraktionstechnik. Im Headspace-Modus (HS) wurde SPME in den letzten Jahren für die Bestimmung von Rest mono meren und gesund heits gefährdenden, leichtflüchtigen organischen Verbindungen (VOCs) in Kunststoffen verwendet.
Solid blend samples of poly(acrylonitrile-co-1,3-butadiene-co-styrene) (ABS) and polyamide 6 (PA 6) were characterized by analytical pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and analytical pyrolysis-gas chromatography with flame ionization detector (Py-GC/FID) at 700 °C, respectively. The separated compounds were identified using the mass spectral library as well as by calculation of the relative retentions. These blends have been chosen, since they play a dominant role in the automotive and other industries.
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.
The global production of plastics in 2014 was already 311 million tons, of which 59 million tons were produced in Europe [1]. At least 270,000 tons of plastic were floating as a giant plastic island on the seas [2]. The waste carpet in the North Pacific (Great Pacific Garbage Patch), which was discovered in 1997, has put together about the size of Germany and France and contains an estimated one million plastic parts per square kilometre [2].
