TGA/STA-GC-MS Coupling

Highest resolution in Evolved Gas Analysis (EGA)

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.

Technique

TG-GC-MS - Technical Specifications (subject to change)

  • Mass range: 1.6 u to 1050 u (*)
  • Mass filter: monolithic hyperbolic quadrupole
  • Mass resolution: Unique mass (adjustable by tuning)
  • Ionization: non-coated inert electron impact source
  • Ionization energy standard 70 eV (selectable range: 5 eV to 241.5 eV)
  • 2 filaments
  • Detector: triple axis SEM with long life EM
  • Scan rates: 12.500 u/s (electronically), 8.000 u/s write-to-disk

    (*): unified atomic mass unit
  • Heated furnace adapter, max. 300°C (for MS, FTIR or GC-MS coupling)
  • Heated transfer line: Glass-lined steel tubing, max. 300°C (forced flow by pumping through the sampling loop)
  • Bypass system for excess gas at the furnace
  • Valve box can be heated to 300°C, with sampling loop of 250 µl
  • Unis 500 injector (split, splitless) max. 450°C
  • GC column: Standard HP-5ms capillary (30 m, max. 325°C, other columns available according to specific application)
  • Fast change of capillary columns without interruption of MS vacuum (swap'n go, JAS)
  • Column Furnace: 35°C to 425°C

Software

The GC-MS is controlled by the versatile Agilent Chemstation software. When coupled with TG/STA, the start of Chemstation is triggered via the Proteus® software in two modes:

  • Continuous run of the GC-MS with periodic injection of the sample gas (start at selectable time or temperature in relevant segments of the TG/STA temperature program)
  • Event-controlled run at selectable thresholds of the mass loss rate (automatic start of Chemstation software when the threshold is exceeded, with the possibility of multi-segment selection of different thresholds). The heating of the TG/STA is on hold for the duration of the GC furnace program; then heating is automatically resumed until the next threshold is reached.

The resulting GC-MS total ion chromatograms (TIC) can be imported into the Proteus® software and displayed, evaluated, stored, and/or exported together with the TG, DTG, DSC, and other loaded data.

The retention peaks in the TIC, which can be used to identify individual components in the analyzed gas mixture, can be easily evaluated with the Agilent Data Analysis software by double clicking to show the underlying mass spectra. With the next mouse click, the NIST 08 MS library – containing around 220,000 EI mass spectra of more than 190,000 substances – is searched for the measured spectra and displays the best hits. The NIST 08 MS library and search program are included in the standard package.
In stand-alone operation of the GC-MS, the Chemstation software operates independently of Proteus® (either multitasking with Proteus® or on a separate PC).

You can use the following software with this product:

Proteus® SoftwareAdvanced Software

Applications

The primary scope of TG-GC-MS coupling is to detect, separate and analyze organic components. It is also possible to use the coupled GC-MS for detailed gas analysis to further improve the temperature-programmed pyrolysis of organic materials, biomass, renewable solid fuels, carbonaceous materials, and polymers in the TG/STA. The volatile products emitted during combustion processes can be determined with high sensitivity and resolution at various oxygen content levels.

The highly sensitive GC-MS gas detection and identification capabilities allow for improved analysis of additives, stabilizers, and residual solvents in food, pharmaceuticals, cosmetics, and polymers.

Literature

Brochure

Brochure

Product brochure: Evolved Gas Analysis; Methods, Technique, Applications, 20 pages

Brochure

Application brochure: Thermoplastics, Thermoplastic Elastomers, Elastomers and Thermosets, 36 pages

Brochure

Application Volume: Coupling of Thermal Analysis and Gas Analysis; Techniques and Applications, order form

Poster

Poster

Our poster “Thermal Properties of the Elements” shows the following values at a glance: melting point, boiling point, specific heat, heat of fusion, thermal expansion coefficient, thermal conductivity and density.

Poster

Our poster “Thermal Properties of Polymers” offers the following characteristic values at a glance: Glass transition temperature, heat of fusion and melting temperature, decomposition temperature, E modulus, coefficient of thermal expansion, specific heat capacity, thermal conductivity and density.