Gas Chromatography Mass Spectrometry, GC-MS Analysis
Gas chromatography (GC) is used to separates mixtures into individual components using a temperature-controlled capillary column. Smaller molecules with lower boiling points are travel down the column more quickly than larger molecules with higher boiling point.
Mass spectrometry (MS) is used to identify the various components from their mass spectra. Each compound has a unique or near unique mass spectrum that can be compared with mass spectral databases and thus identified. Through use of standards, quantitation is also possible.
GCMS analysis can work on liquids, gases and solids. For liquids, the sample is directly injected into the GC. For gases, gas tight syringes are used to transfer the gaseous components directly into the GC. For solids, the analysis is carried out either by solvent extraction, outgassing or pyrolysis.
Outgassing a sample via application of heat (thermal desorption) is a special sampling technique also known as Dynamic Headspace Analysis (HSA). Volatile organic components in the solid matrix are removed by heated gas flow. In dynamic HSA, the sample is placed in a chamber and heated to a specified temperature for a specified time. The outgassed components are continually removed and collected in a cold trap. They are then analyzed by GC-MS. The maximum allowable temperature for this method is 300ºC, and the maximum sample size is 1"×4".
Pyrolysis is another sampling technique for the analysis of materials that cannot be directly injected into the GC-MS. By applying heat directly to a sample, the molecule can be broken down in a reproducible way. The smaller molecules are then introduced into the GC and analyzed by GC-MS. By this method, probe temperatures of up to 1400ºC can be used.
- Identifying and quantifying volatile organic compounds in mixtures
- Outgassing studies
- Testing for residual solvents
- Liquid or gas injections
- Evaluating extracts from plastics
- Evaluating contaminants on semiconductor wafers (thermal desorption)
Signal Detected: Molecular ions & characteristic fragment ions
Elements Detected: Molecular ions up to m/z 800
400ng (full scan)
- Identification of organic components by separating complex mixtures
- Quantitative analysis
- Trace-level determination of organic contamination (low to mid-ppb level for liquids and low nanogram level for solids (Dynamic Headspace Analysis)
- Sample must either be volatile or capable of derivatization
- If the sample is not volatile (as in headspace, pyrolysis, or direct probe), then the analyzed material must be volatile
- Biomedical/biotechnology (primary)
- Electronics (primary)
- Compound Semiconductor
- Data Storage
- Industrial Products
- Solar Photovoltaics
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