Gas chromatography (GC) with mass spectrometry (MS) is used to separate and analyze compounds from a complex mixture that can be readily vaporized (typically non-polar compounds below 500 Da). The GC vaporizes the sample, then separates and analyzes the various components. Each component produces a specific retention time and EI mass spectrum of the eluting components. The size of the peaks is proportional to the quantity of the molecule. The compound can be identified by the GC retention time, the parent ion, and fragmentation pattern as searched by a database of known compounds. The retention time can help to differentiate between some compounds.
- This service is typically performed on the Thermo Scientific Exploris GC-MS Orbitrap. The high resolution of the Orbitrap mass spectrometer allows ultra-high mass accuracy of the GC separated analytes and their EI fragmentation pattern.
- If the mass of the precursor is primarily desired, especially for those analytes where the EI fragmentation pattern is unknown or similar to many other analytes, a soft ionization source, CI, can also be used.
- For projects now requiring GC separation or quantitation, the GC can be bypassed using a direct insertion probe (e.g., DIP or DEP).
- For projects not needing high mass resolution, a nominal mass GC-MS is available. The Thermo Scientific ISQ GC-MS can perform routine, high-throughput GC-MS analysis using unit mass precursor and EI fragmentation spectrum matching.
- For headspace sample analysis, the ISQ GC-MS comes equipped with a headspace sampler.