Analyzing Failure Using Pyrolysis-GC–MS

The Column spoke to Peter Kusch of the Bonn-Rhein-Sieg University of Applied Sciences in Rheinbach, Germany, about analyzing failure in the automotive industry.

Q: What is the focus of your research at the present time?

A: My research at the Department of Applied Natural Sciences at the Bonn-Rhein-Sieg University of Applied Sciences (Rheinbach, Germany) focuses on the application of the analytical pyrolysis-gas chromatography–mass spectrometry (Py-GC–MS) and headspace–solid-phase microextraction-GC–MS (HS-SPME-GC–MS) for characterization of polymeric materials and components from many branches of manufacturing and building industry. Pyrolysis involves thermal fragmentation of the high molecular analytical sample at elevated temperature (500–1400 °C) in the presence of an inert gas (helium).

Photo Credit: Pixhook/Getty Images

The pyrolysis products are separated by performing GC using a fused-silica capillary column and subsequently identified by interpretation of the obtained mass spectra or by using mass spectral libraries, such as NIST/EPA/NIH, Wiley, MPW, or Norman Mass Bank.^1–3

The HS-SPME-GC–MS technique will be used in our laboratory for determination of residual monomers and other volatile organic compounds (VOCs) and additives (antioxidants, plasticizers) in polymers and copolymers.

Q: What are the main objectives of your research group?

A: In the first decade of the 21st century there was the EUREKA-project "Boiltreat E! 2426" in cooperation with the Institute of Heavy Organic Synthesis "Blachownia" (Kedzierzyn-Kozle, Poland) and other project partners from France, Lithuania, and Romania. The aim of the project was the development and implementation of a new technology for water chemical treatment in the energy industry. Our laboratory was responsible for the GC–MS identification of thermostable long-chain alkyl amines and alkyl diamines and analysis of boiler water samples from the power plant by using the new anti-corrosive and anti-scaling formulations.⁴

In recent years, however, the focus has been on the characterization of polymeric materials and failure analysis, especially in the automotive industry. In my work, besides projects, I am also involved under the auspices of the German Chemical Society (Gesellschaft Deutscher Chemiker, Frankfurt) together with my colleagues Professor Gerd Knupp and M. Eng. Johannes Steinhaus in the implementation of the course "Application of Pyrolysis-Gas Chromatography/Mass Spectrometry for Characterization of Plastics" for participants from industry, research institutes, and academia from Germany, Austria, and Switzerland.

Q: What is "failure analysis" in the automotive industry?

A: Failure of the structure of materials or components often results in accidents and plant shutdowns, resulting in hefty compensations. Failure analysis is the process of collecting and analyzing data to determine the cause of a failure and to take action to prevent it from happening again. It is an important discipline in many branches of the manufacturing industry, such as the automotive industry. Failure analyses of automotive materials or components help to identify root causes for degradation, malfunction, damage, or ageing. Various analytical techniques, like microscopy imaging, scanning electron microscopy (SEM), energy dispersive x-ray analysis (EDX), UV–vis spectrometry, Fourier-transform infrared spectrometry (FTIR), nuclear magnetic resonance (NMR), and time-of-flight secondary ion mass spectrometry (TOF-SIMS) are used for the clearing of raw material failure, manufacturing, function, design, or storage errors of various plastic or metal components from the automotive industry.

For more than 10 years, our laboratory has been involved in failure analysis projects in the automotive industry using py-GC–MS. The high success rate for solving problems and the satisfaction of our clients have convinced us that this analytical technique is well suited for failure analysis in the automotive industry. The obtained analytical results are then used for troubleshooting and remedial action of the technological process. Some of the results we have obtained have been presented at international symposia and published in analytical journals.^5–8

Q: What are the applications of pyrolysis gas chromatography–mass spectrometry in failure analysis? What are the advantages over other methods?

A: Practical application of these hyphenated analytical techniques in our laboratory ranges from: case studies of automotive components; failure analysis of failed hydraulic cylinders, membranes, and packaging of hydraulic cylinders; sealing rings, tyre materials, and additives; auto paints, auto wrapping foils, auto catalysts, mineral oils, and brake fluids to identification of plastic particles from industrial filter fins; residues of fittings of refrigerant compressors; residues from a valve block of a medical respirator; identification of dental filling materials; detection of counterfeits of plastic and rubber products; modules from building industry; fouling from a roller bearing; adhesives; sealing compounds; cesspit residues from an extruder or polyethylene re-granulate from mechanical recycling process; or polymer residues in recycled aluminum.

Py-GC–MS allows the direct analysis of very small sample amounts (5–200 μg) without the need of time-consuming sample preparation. The identification of complex mixtures or blends as well as identification of samples with so-called "difficult matrix" are also possible in many cases.

Q: What are the challenges and difficulties in applying pyrolysis gas chromatography–mass spectrometry to failure analysis? How can they be overcome?

A: The increasing use of polymeric materials in the automotive industry requires sensitive and reliable methods for its analysis. For the failure analysis in motor vehicles there is often a lack of information about the component itself, such as chemical composition, temperature resistance, possible contaminants, or mechanical properties. The damage range is usually limited and not always homogeneous. There are often only small amounts of samples available to clarify the damage, which may be important for recognizing the cause of damage. Traditional analytical techniques used for characterization of polymers/copolymers, such as thermal analysis (TA) 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. A lot of information about dysfunction of automobile parts can be obtained from the fouling material on the surface of the failed parts. In such cases the sampling can be made by rubbing the affected surface with the quartz glass wool followed by the py-GC–MS of the enriched wool. Another problem could be the difficulty in the interpretation of pyrograms of complex mixtures or blends, because of the large number of decomposition products. In such cases, an extended analysis is required. The relatively long duration of most py-GC–MS measurements could probably be shortened by application of fast-GC–MS.

Q: Are there other applications where pyrolysis gas chromatography–mass spectrometry is commonly used?

A: Py-GC–MS can be applied to research and development of new materials, quality control, characterization and competitor product evaluation, medicine, biology and biotechnology, geology, airspace, and environmental analysis to forensic purposes or conservation and restoration of cultural heritage. These applications cover analysis and identification of polymers/copolymers and additives in components of automobiles, tyres, packaging materials, textile fibres, coatings, adhesives, half-finished products for electronics, paints, or varnishes, lacquers, leather, paper, or wood products, food, pharmaceuticals, surfactants, and fragrances.

Q: Where will your research take you in the future?

A: I have experience in the application of Curie-point pyrolyzers and furance pyrolyzers but would like to test the heated filament and laser pyrolyzers. I am also interested in the hyphenation of pyrolysis with multidimensional and comprehensive GC and MS.

References

1. S.E. Stein, J. Am. Soc. Mass Spectrom. 5(4), 316–323 (1994).

2. P. Ausloos et al., J. Am. Soc. Mass Spectrom. 10(4), 287–299 (1999).

3. O.D. Sparkman, Z.E. Penton, and F.G. Kitson, Gas Chromatography and Mass Spectrometry. A Practical Guide, Second Edition (Elsevier Inc., Burlington, USA, 2011).

4. P. Kusch, G. Knupp, M. Kozupa, J. Ilowska, and M. Majchrzak, in Developments in Corrosion Protection, M. Aliofkhazraei, Ed. (InTech, Rijeka, Croatia, 2014), pp. 413–429.

5. P. Kusch, in Agricultural, Biomedical and Industrial Applications, M.A. Mohd, Ed. (InTech, Rijeka, Croatia, 2012), pp. 343–362.

6. P. Kusch, G. Knupp, W. Fink, D. Schroeder-Obst, V. Obst, and J. Steinhaus, LCGC Europe 27(6), 296–303 (2014).

7. P. Kusch, V. Obst, D. Schroeder-Obst, W. Fink, G. Knupp, and J. Steinhaus, Eng. Fail. Anal. 35, 114–124 (2013).

8. P. Kusch, LCGC North America 13(3), 248–254 (2013).

Peter Kusch studied chemistry at the Pedagogical University in Opole, Poland, and gained his doctorate degree in organic chemical technology at the Poznań University of Technology, Poland. From 1977 to 1988 he worked as an analytical chemist at the Institute of Heavy Organic Synthesis "Blachownia" (Kędzierzyn-Koźle, Poland). After moving with the family to Germany, he worked for several years in the Fischer GmbH company (Meckenheim/Bonn, Germany) as laboratory manager and specialist for analytical pyrolysis and chromatography. Since 1998 he has been a scientific co-worker at the Department of Natural Sciences of the Bonn-Rhein-Sieg University of Applied Sciences in Rheinbach, Germany. He is an author/co-author of over 80 scientific publications, seven book chapters, and 11 patents in the area of chromatography, mass spectrometry, and analytical pyrolysis. Peter is a reviewer for several international journals in the analytical chemistry field and a member of the American Chemical Society (ACS).

E-mail: peter.kusch@h-brs.de

Website: https://www.h-brs.de