Combined techniques - GC-MS

As discussed in Chapter 7, gas chromatography (GC) is used to separate complex mixtures of volatile organic compounds. However, unless pure authentic standards are also analyzed to compare retention times, it is not possible to identify the components by GC alone. However, by connecting the output of a GC to a mass spectrometer, and by removing the carrier gas to maintain the low pressures required, it is possible to both separate and identify these complex mixtures. This method is the gold standard for the identification of organic samples, if they are sufficiently volatile. 

The instrumental design is similar to that of other mass spectrometers described above, with the end of the GC column directly inserted into the ion 

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