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Why are gas chromatography and mass spectrometry often combined?

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Gas chromatography and mass spectrometry are often combined to create a powerful analytical tool because they address complementary needs in the identification of chemical substances.

Gas chromatography is highly effective at separating complex mixtures of volatile substances into their individual component fractions as they move through a column at different speeds. However, while it can signal the arrival of a component, it requires additional methods for definitive identification.12

Mass spectrometry serves as a highly specific detector when coupled with this separation process. By ionizing and fragmenting the molecules, it produces a characteristic mass spectrum that allows for the precise identification of the separated components.23

When used together as a gas chromatograph–mass spectrometer, the chromatograph ensures that fractions of a mixture arrive at the mass spectrometer's ion source in succession. This allows for highly reliable mass analyses of each individual component, enabling chemists to identify substances within complex mixtures with great accuracy.23