Gas Chromatography (GC) is a type of chromatography used for separating and analyzing compounds that can be vaporized without decomposition. VOCs (Volatile Organic Compounds) and SVOCs (Semi-Volatile Organic Compounds) are normally analyzed, but other compounds can be analyzed previous derivatization.
A gaseous or liquid sample is injected in the carrier gas stream and interact with the stationary phase of the chromatographic column, that is commonly a microscopic layer of viscous liquid or solid particles. The separation of the constituents of a mixture is due to the different interaction of each compound with the stationary phase and/or by boiling point.
The time that each component takes to reach the detector (retention time) is the principle parameter used for the identification. Each component is detected as a chromatographic peak (ideally with Gaussian shape) and the area of the peak is used for quantification: the results can be expressed as Area Percentage (area of each peak vs sum of the area of all the peaks in the chromatogram) or with a calibration line (using response factors).
Different detectors are used to reach different goals in terms of sensibility (from ppb to percent), selectivity and specificity.
