Gas Chromatography with Mass Spectrometry


Composition of elastomers and detection of ingredients

Significance and Test Procedure

Gas chromatography with coupled mass spectrometry (GC/MS) allows a deeper insight into the composition of elastomers. It is an analytical method that can be used to characterise almost all materials, whether solid or liquid, on very small sample quantities of a few micrograms without time-consuming sample preparation. It provides information about the type of plastics, the composition of materials, additives or other substances contained in the materials.

There are different GC-MS methods that are suitable for analysing polymers and other materials. The detection limits are generally very low and lie in the ppm range for all variants of this analytical technique. Therefore, even the smallest sample quantities are sufficient to detect even the finest traces of individual substances. In a sense, the use of GC/MS begins where IR analysis ends.

Significance of Pyrolysis GC-MS for Application Technology

GC/MS is primarily used for failure analysis of elastomer and other polymer products. It can be used, for example, to analyse diffused foreign substances in elastomers and thus make reliable statements about a possible chemical attack.

This analytical method is also becoming increasingly important in the detection of substances that are classified as harmful to health or the environment. In our test laboratory, we use GC/MS methods, for example, to detect organic emissions of non-metallic automotive materials in accordance with VDA 278 or to determine the content of siloxanes in accordance with PV 3055 and PV 3040.

In addition, GC/MS allows quantitative and qualitative statements to be made on the composition of elastomers and other plastics, to characterise materials, to compare them with each other or to assess newly developed materials. Finally, the data obtained in GC/MS create a reliable basis for the quality assurance of polymer products.

Testing by means of GC/MS

All types of GC/MS are based on the same basic principle: heating – separating – analysing.

For the analysis, a sample is heated and converted into gaseous state. The resulting gas mixture passes through a channel, the so-called capillary separation column, and is thereby split into its components for the subsequent analysis. The chromatograms and mass spectra obtained during the analysis allow substances to be detected and the nature of the components to be investigated.

One of the main differences between the available GC/MS measurement methods is the temperature at which they work. If the temperature is above the decomposition temperature of a polymer matrix, pyrolysis of the material occurs. If temperatures below this decomposition limit are used, the matrix remains intact. In this case, we are dealing with thermodesorption.

When working with polymers, both high and low temperatures can be useful, depending on the objective, in order to achieve the best possible analytical results.

GC/MS methods

Thus, in our analytics department we examine elastomers and other plastics with the following GC/MS measuring methods:

Pyrolysis gas chromatography (PY-GC/MS)

Heating and decomposition


A very frequently used method for polymers is pyrolysis gas chromatography. It can be used to thoroughly examine the material structure and the organic additives contained in a polymer. With PY-GC/MS, very small sample quantities of only 2 – 500 µg are sufficient to obtain meaningful results. It is usually not necessary to prepare the material samples extensively, which means that the effort required for an analysis remains moderate.


A material sample is heated to 500 – 1400 °C, i.e. above the decomposition temperature of the polymer. During this process, a gas mixture is produced that contains both volatile substances and decomposition products of the polymer matrix or additives. This gas mixture is split by means of the capillary separation column and subsequently analysed.


Due to the small sample quantities and the large number of substances in the gas mixture obtained, PY-GC/MS sometimes reaches its limits. For example, the measurement results may be highly scattered in the case of very heterogeneous polymers or the chromatograms determined may become confusing due to the abundance of different substances. In these cases, it is helpful to switch to other GC/MS types or to supplement the investigation with other methods of material analytics.

Double Shot Method

The combination of pyrolysis and thermodesporption


In the double-shot method, the two aforementioned methods are combined in order to analyse volatile and higher-boiling polymeric components separately. The same material sample is first subjected to thermodesorption (TD-GC/MS) and then to pyrolysis (PY-GC/MS).


Although the polymer matrix is finally decomposed, the chromatograms of the pyrolysis gas chromatography remain clearer in this way, since the volatile components have already left the material in the first step.

Thermodesorption Gas Chromatography (TD-GC/MS)

Heating below the decomposition temperature


The analysis with thermodesorption gas chromatography takes place at temperatures below the material-dependent decomposition limit of a polymer. In this process, only the volatile components are extracted from the material. They pass over the capillary separation column and accordingly get split into their individual components for analysis. In this way, the gas mixture obtained contains far fewer different substances and the chromatograms determined are correspondingly clearer.


It is especially tricky to find out the right temperature for TD-GC/MS at which the undestroyed additives are mobilised and the polymer matrix still remains stable. Furthermore, the selection of the sample quantity is also quite challenging. It depends on the proportion of volatile components contained in the polymer and can vary accordingly. The aim is to analyse enough material so that even small amounts of single substances are detected without, however, overloading the capillary separation column. With unknown materials, it is therefore helpful to first carry out a TGA (Thermogravimetric Analysis) to determine the proportion of volatile components.

Headspace Technique (HS-GC/MS)

Heating at low temperatures


The headspace technique also uses rather low temperatures to protect the polymer matrix. Normally, we work below 150 °C here. Unlike the aforementioned methods, however, the material sample is kept in a closed vessel during heating, resulting in an equilibrium between solid, liquid and gaseous. The headspace technique has two variants, a static one (S-HS-GC/MS) and a dynamic one (D-HS-GC/MS), which differ mainly in the way the resulting gas mixture is removed from the vessel.


The headspace technique is particularly convincing for materials with low thermal stability and allows for excellent automation. In addition, HS-GC/MS also supports larger sample quantities of more than 100 mg, which, however, requires somewhat more time and effort for sample preparation.


You will find more detailed information on pyrolysis GC-MS in our examples and technical reports:

Gas chromatography with coupled mass spectroscopy is an important method for the analysis of polymers. The report describes the different GC/MS measurement methods and their possible applications.

In the DICHT! special edition O-Ring Prüflabor Richter you will find a comprehensive overview of common tests and analysis methods in elastomer technology. Discover the collected knowledge about elastomer testing in this issue.