Gas Analysis / Couplings

The QMS 403 Aëolos® quadrupole mass spectrometer is a new compact mass spectrometer with a heated capillary inlet system for routine analysis of gases and, in particular, volatile decomposition products of thermal analysis. This system has been optimized for coupling to differential scanning calorimeters, dilatometers and thermogravimetric analyzers by:

• Increasing the temperature of the entire gas transfer system to 300°C

• An improved single-stage inlet system with a low-reaction fused silica capillary and ultrasonic expansion in the ion source

• Integration of the mass spectrometer software and data exchange for user-friendly operation from the Proteus® thermal analysis software.

The high temperature of the gas transfer system and the absence of pressure reduction orifices practically eliminate condensation of decomposition products during thermal analysis experiments. This achieves a high detection sensitivity and facilitates quantitative detection of all identified gas components.
Via the inlet system with the fused silica capillary, other gas sources can be investigated with the QMS 403 C Aëolos® independent of thermal analysis; for that purpose, the QMS is operated with the self-contained software.

The concept of the NETZSCH thermal analysis instruments has been laid out from the start for coupling with gas analysis systems like the QMS 403 C Aëolos® or an FTIR system with a gas cell, through consistent optimization of the gas paths with complete heating from the furnace to the gas detector. This eliminates gas loss through condensation at cold spots and only very low carrier gas flows are sufficient for complete transfer. The minimal dilution of the volatile sample products released results in high detection sensitivity with the QMS 403 C Aëolos®.

The SKIMMER coupling system with a quadrupole mass spectrometer (QMS) is worldwide the most sensitive system for thermoanalytical gas analysis. The coupling takes place directly in the furnace of the STA 409 CD. The first pressure reduction stage is arranged directly above the sample container. The orifice is so designed that it works as divergent nozzle. The SKIMMER is the second pressure reduction stage and arranged in the range of the forming compression area behind the nozzle. The distance between sample and high-vacuum component is only ca. 12 mm. As the entire system has sample temperature, condensation during gas transfer are excluded. Due to the vertical gas flow in the sample area and the short distances a complete transfer of the evolving gases is ensured. This again results in short retention times and an extremely high sensitivity.

GC is a high-resolution method for separating volatile and semi-volatile compounds. The gas mixtures are separated based on the differences in component distribution between a stationary phase (e.g. inner coating of a capillary) and a mobile phase (purge gas, e.g. helium). Since this gas separation in the GC column takes a certain amount of time – the duration of which depends upon sample characteristics, column flow rate, column length, and stationary and mobile phase – it is not possible to couple directly into the GC with a continuous online sample gas flow. Our solution, therefore, was to develop a direct coupling in a quasi continuous mode by using heated automatic valves, which allows for software-controlled gas sampling (flow-through sampling loop) and gas injection even at short intervals.

• Unique TG/STA-GC-MS coupling solution with event-controlled or temperature-dependent triggering

• Perfectly heated gas transfer (300°C) from the TG/STA to the valve box and the injector at the GC

• Fast and wide-range QMS for analysis of the gas chromatogram

• Independent application of GC-MS for liquid/gas injection at any time

For GC-MS coupling, we rely on the world-renowned supplier, Agilent, along with our partner, Joint Analytical Systems (JAS). This allows for perfect GC-MS supply and service quality, as we at NETZSCH expect of any entity with which we do business, in order to guarantee optimized performance for our own products.

Especially in the polymer range as well as in the pharmaceutical and chemical industry, the knowledge of the evolving gases during a process, a curing/cross-linking, a decomposition or any other reaction is of great interest.
For the vacuum-tight thermal balances and simultaneous thermal analysis instruments TG 209F1 Iris®, TG/STA 449 F3 Jupiter® and TG/STA 449 F1 Jupiter®, but also for the dynamic differential calorimeters DSC 404 F1 Pegasus® and DSC 204 F1 Phoenix® NETZSCH offers you efficient coupling systems for a Fourier-Transform Infrared spectrometer (FTIR). The transfer line and the connection adaptors to the furnaces are heatable up to 230°C to prevent a condensation of the decomposition products as far as possible. For the spectra interpretation extensive gas phases libraries are available.