Varian Gas Chromatography-Mass Spectrometer (GC-MS) Description

Gas chromatography-mass spectrometry (GC/MS) is an instrumental technique, comprising a gas chromatograph (GC) coupled to a mass spectrometer (MS), by which complex mixtures of chemicals may be separated, identified and quantified. Typical applications include:

  • Analysis of industrial products for quality control
  • Formulation analysis of organic mixtures.
  • Trace analysis of organic species for environmental, regulatory and industrial applications with detection limits down to ppb trace levels
  • Volatile Organic Compounds (VOC) analysis of paint emissions when coupled with a FLEC cell and Automatic Thermal Desorption ATD system.

Technical Specifications:

GC Instrument – Varian 450 Gas Chromatograph fitted with both a FID (Flame Ionisation Detector) and a 220 Mass Spectrometer detector. Additional accessories on the machine include:

  • A CTC CombiPAL Autosampler which allows for a high throughput of liquid samples. The autosampler includes both Headspace and Liquid injection techniques.
  • CTC SPME (solid phase micro extraction) option for the CombiPAL which reduces the time required for sample preparation and eliminates the use of large volumes of extraction solvents.
  • Quick-Switch Valve, Automatic 230V, which allows the facile and rapid switching between two different columns and/or injectors or detectors, minimizing the downtime of the machine.
  • CDS Pyroprobe 5200 pyrolyser. Pyrolysis, coupled with GC (Py-GC), permits the analysis of samples which were previously unsuitable for analysis without lengthy extractions or derivatisations.
  • Perkin Elmer ATD (Automatic Thermal Desorption) 400 which is used for the analysis of VOCs when used in conjunction with a FLEC Cell and Tenax TA™ tubes.
  • NIST 05 Library and AMDIS search and deconvolution program.

Principle:

Gas Chromatography- Mass Spectrometry (GC-MS) is a hybrid technique which couples the powerful separation technique of gas chromatography with the specific characterisation ability of mass spectrometry. It is useful technique for the determination of volatile and semi-volatile, thermally stable compounds. The technique involves passing a “mobile phase” which is a carrier gas, containing the sample, through a “stationary phase” which is a column with varying affinity for the components of interest. The components injected onto the column are separated in the column based on this affinity. Individual analytes are then detected as they emerge from the end of the column through the detector. The advantage of using the Mass Spec is that it gives information regarding the structure and Molecular weight of an analyte. In principle each Mass Spectrum is unique and can be used as a “fingerprint” to characterise the sample.

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