Organic Analytics

Gas Chromatography

Gas chromatography (GC) in conjunction with various detectors is a powerful analytical method for the separation, identification and quantification of volatile compounds in a sample. It is based on the principle of the distribution and separation of gaseous compounds between a stationary phase (usually a coated capillary column) and an inert mobile gas (carrier gas) that transports the sample through the column. Gas chromatography has established itself as an efficient method for separating complex samples in environmental analysis, materials science, the food and beverage industry, pharmaceutical analysis, forensics, etc.

Contact person: Dr. Tim Hammerschick

Ein Chemiker sitzt vor einem Gaschromatographen mit Massenspektrometer (GC-MS)

Separation of volatile and semi-volatile (to semi-volatile) organic substance mixtures using capillary separation columns and detection of the individual components using a mass spectrometer. Direct injection/dispensing of liquids and dissolved solids. Measurement of gaseous components after cryo-enrichment.

Contact person: Dr. Tim Hammerschick

In pyrolysis (Py), the sample material is strongly heated in an inert gas environment under controlled conditions to induce thermal decomposition. This breaks down high molecular weight compounds into smaller fragments. These fragments are then separated using gas chromatography (GC) and detected using mass spectrometry (MS). Using the resulting mass spectra of the fragments produced during pyrolysis, it is possible to identify them and determine their structure. Conclusions can then be drawn about the composition of the starting material from the characteristic decomposition products.

The advantage of Py-GC-MS over other analytical techniques such as LC-MS and GC-MS lies in the wider range of matrices that can be analyzed, including gases, liquids, solids and cross-linked polymeric materials (solvent-insoluble materials). With this analytical technique, for example, the smallest quantities of complex polymer samples (30 µg - 1 mg) such as plastics, coatings, rubber, resins, cellulose, etc. can often be analyzed directly without prior sample preparation. Py-GC-MS is used, for example, in materials science to determine the composition of polymers by providing information on monomers, copolymers and additives.

Pyrolysis is often preceded by additional thermodesorption (TD) to obtain further information. In the so-called "double-shot technique", volatile and semi-volatile compounds are released from a solid or liquid sample at a selected temperature in a first step, the thermodesorption, cryofocused with liquid nitrogen and then separated into the individual components by gas chromatography. TD/Py-GC/MS has the advantage that the (semi-)volatile compounds are selectively extracted from the main matrix at one (or more) specific temperature(s) by thermodesorption, which increases the sensitivity of their analysis.

Facts:

Sample quantity: from 30 µg

Contact person: Dr. Tim Hammerschick

Darstellung, dass die Pyrolyse-Gaschromatographie für gasförmige, flüssige und feste Proben geeignet ist

The very sensitive and robust flame ionization detector (FID) is ideal for the detection of organic compounds. Coupling with gas chromatography (GC/FID) is a proven method for quality control of solvents or petrochemical products and is often used in addition to GC/MS analyses. At ATU GmbH, the GC/FID coupling is mainly used to determine the residual oil content in compressed air samples. To determine the total residual oil content, the compressed air is first passed through a borosilicate fiber filter during sampling to adsorb the aerosol fraction and then through an activated carbon tube to adsorb the volatile organic compounds (VOC). After solvent extraction, the analysis is carried out using GC/FID in accordance with ISO 8573-2 and ISO 8573-5. By separating the oil components using GC and detecting them using FID, even the smallest oil residues can be identified and detected. This is crucial for compliance with the required limit values in various industries such as food processing, pharmaceuticals and electronics manufacturing.

Contact person: Dr. Tim Hammerschick, Susi Reutz

In gas chromatography with a helium ionization detector (HID), helium is used as a carrier gas. The helium plasma ionized in the detector then ionizes the fractions coming from the separation column. The electrical current caused by the ionized components serves as the measurement signal. We also have a thermal conductivity detector (WLD or TCD). With these two detectors, we cover a broad spectrum in the analysis of gaseous samples:

Air analyses: trace substances in room air + ambient air
Determination of impurities in various high-purity gases (O2, N2, H2, He)
Determination of impurities in the trace range in critical process gases: HCl, NH3, Silanes

Contact person: Hans-Dieter Schmidt

Residual Gas Mass Spectrometry

As part of its comprehensive analysis services, ATU also offers its customers classic and application-oriented mass spectrometry-based residual gas analysis.

Residual gas analyses using quadrupole or time-of-flight mass spectrometry offer the following advantages, among others:

Direct qualitative/quantitative determination of trace gases down to the ppb/ppt range, in gas and gas mixtures, in plasmas and even in liquids using gas-permeable membranes.
Qualitative/quantitative evaluation of the level of contamination and the vacuum strength of ultra-cleaned parts made of metallic, ceramic or polymeric materials by exposure for several hours in an ultra-high vacuum at room or elevated temperatures in accordance with OEM specifications (e.g. Zeiss / ASML Grade 1).
Absolutely non-destructive testing of high-quality parts in an ultra-clean environment in an ultra-high vacuum (UHV). Testing the space suitability of components and encapsulated modules.

Contact person: Hans-Dieter Schmidt

Analysis of Liquids using Membrane Introduction Mass Spectrometry (MIMS)

Mass spectrometry with membrane introduction mass spectrometry (MIMS) can be used to transfer volatile substances dissolved in water into the gas phase so that they can be analyzed using mass spectrometry. In this process, volatile compounds diffuse from the liquid through the semi-permeable membrane.

Contact person: Hans-Dieter Schmidt

Typisches Spektrum, das mittels Massenspektrometrie mit Membraneinlass aufgenommen wurde

Infrared Spektroscopy

Fourier transform infrared spectroscopy (FTIR) can be used to obtain information to identify organic materials. Special micro-techniques can also be used to examine particles, fibers, surfaces and thin layers.

Facts:

Minimum layer thickness: 100 nm
Minimum spot size: 100 µm

Contact person: Susi Reutz

Eine Chemikerin arbeitet an einem IR-Spektrometer (FTIR)

High performance liquid chromatography (HPLC)

High performance liquid chromatography (HPLC) is an analytical method used to separate, identify and quantify individual components in liquid mixtures.

The applications of HPLC are manifold, e.g.:

Purity testing in the quality control of chemicals and chemical products
Detection of pollutants in the environment
Quality control and evaluation of additives and contaminants in foodstuffs
Determination of hormones, proteins, nucleic acids and other molecules in biochemistry

HPLC offers the following advantages:

high resolution for separation
high sensitivity in analysis
even the smallest sample quantities can be analyzed

Contact persons: Susi Reutz, Dr. Tim Hammerschick

Function:

The sample mixtures dissolved in liquids are pressed together with an eluent under high pressure through a column filled with materials of a stationary phase. The components to be separated interact differently with the stationary phase and are thus retained for different lengths of time, which leads to their separation.

The separated components coming from the separation column can be detected and determined by a variety of substance-specific detectors. In addition to fluorescence and refractometric detectors, mass-selective HPLC detectors with very high sensitivity and selectivity have been available for some years now.

We use a UV-VIS detector with variable wavelength for the detection of compounds with chromophores.

On- & Off-Line TOC

Total Organic Carbon (TOC) is a key summary parameter in chemical analysis and describes the total amount of organic contaminants in a sample. To determine this, the inorganic carbon content (Total Inorganic Carbon, TIC) is first measured. Subsequently, all carbon-containing compounds present in the sample are converted to carbon dioxide by means of UV oxidation and measured as the total carbon content (Total Carbon, TC). The TOC content is calculated from the difference between TC and TIC.

Depending on the application, detection is carried out using infrared spectrometry or conductometric methods. Our analytical instruments achieve detection limits of up to 25 µg/L (ppb) in ultrapure water (UPW) and up to 1.0 mg/L (ppm) in chemical matrices.

For maximum flexibility, we also offer TOC analyses directly at your premises: our portable analyser enables measurements with a detection limit of up to 0.2 µg/L (ppb).

Contact person: Falko Geisler

Organic Analytics

Gas Chromatography

Special gas chromatographic methods

Gas Chromatography with Mass Spectrometry (GC-MS)

Pyrolysis Gas Chromatography with Mass Spectrometry (Py-GC-MS)

Gas Chromatography with Flame Ionization Detector (GC-FID)

Gas chromatography with Helium Ionization Detector / Thermal Conductivity Detector (GC-HID/TCD)

Residual Gas Mass Spectrometry

Analysis of Liquids using Membrane Introduction Mass Spectrometry (MIMS)

Infrared Spektroscopy

High performance liquid chromatography (HPLC)

On- & Off-Line TOC