Gas chromatography with mass spectrometric detection (GC-MS)
The method is based on a gas chromatographic seperation of volatile compounds followed by their mass spectrometric detection.
Principle of the method:
The most important advantage of the method - combination of effective separation and identification. It allows quick identification of compounds in very complex mixtures and matrices.
Other method advantages:
Principle of the method:
- injected sample is evaporated in the inlet of gas chromatograph from where it is transferred to the column (fully or partially)
- most volatile compounds pass through the column with different speed, thus leading to their separation
- to help less volatile compounds passing through the column, it's temperature is slowly increased
- from the column, compounds pass through thermostatted interface and reach ion source where they are ionizaed (mostly by electron impact)
- formed ions are pushed to a mass analyzer (e.g., quadrupole) where they are separated according to their mass-to-charge ratio (m/z)
- from a quadrupole, ions reach the detector that determines their quantity
- as a result, three-dimensional array of data is obtained - every point of chromatogram contains mass spectrum
The most important advantage of the method - combination of effective separation and identification. It allows quick identification of compounds in very complex mixtures and matrices.
Other method advantages:
- high selectivity (by selected ions) - allows increse the separation efficiency
- high sensitivity: <1 picogram in selected ions monitoring (SIM) mode
- possibility to simultaneously determine large number of compounds of a different nature
- possibility of quick semi-qantitative analysis of volatile samples (gasoline, organic solvents, gases, etc.) using normalization of peak areas
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