When do you use gas chromatography and mass spectrometry (GC–MS) at the same time?
1 Answer
The point of using Mass Spectroscopy is to fragment the sample, and through understanding how the molecule fragments into particular
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Gas Chromatography is a gas-phase elution method that essentially separates sample into its component parts and identifies a component's mass based on the amount of time it spends traveling through a tube. The mass is automatically cross-referenced with a database. Often, microliters are used to deliver sample, which is at once delicate and conserving sample.
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Coupling the two techniques as GC-MS combines the two goals together to separate samples into component compounds, determine relative abundances of significant compounds, and find out what is in the sample.
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GC is the injection (syringe), vaporization (in oven), and separation (amount of "lag" in sample as it goes through the 30-ft tube) method, and MS becomes the ionization (using the ion source) and fragmentation (using the mass analyzer) method. Then the electron multiplier detects the signal and you get both a mass spectrum and a gas chromatogram to work with! :)
One example is identifying omega fatty acids in egg yolks. You kind of know what's there, but you aren't sure what fatty acids specifically or in what relative abundances.
