Gas chromatography is a separation technique in which the mobile phase is a gas and separation is always carried out in a column ^[1][1]. A vaporized sample is transported by an inert carrier gas through a column containing a stationary phase, and the components of the sample are separated on the basis of their differential distribution between the gaseous mobile phase and the stationary phase ^[1][2]. Separation arises because sample components possess different vapor pressures and different affinities for the stationary phase, so that they migrate through the column at different rates and emerge at characteristic retention times ^[2]. The technique is applicable to thermally stable, volatile and semi-volatile substances, and the column may be of the packed or capillary type, with the stationary phase selected according to the chemical nature of the analytes ^[1]. The instrumental system comprises an injector, a column, a detector, and a carrier-gas supply with flow and pressure control, and the detector generates a signal proportional to the quantity of each separated component as it elutes from the column. Gas chromatography encompasses gas–liquid and gas–solid modes, depending on whether separation is effected by partition into a liquid stationary phase or by adsorption onto a solid stationary phase ^[1]. Within analytical chemistry and chromatography, the term designates this gas-phase, column-based separation method together with the retention, selectivity, and efficiency parameters through which the separation of volatile analytes is described and optimized ^[1][2].