Usually referred to simply as GC, this is one of the most important and widely used analytical techniques in the fragrance industry, as it is ideally suited to the volatile compounds that are the basis of the industry. It is a means of separating a complex mixture into its components and subsequently quantifying the individual components. As a chromatographic technique, it is based on the partition of analytes between the mobile phase (a gas such as helium, hydrogen or nitrogen) and the liquid stationary phase, which is often coated onto the inner wall of a very narrow fused silica column. The time taken for a material to elute from the column (its retention time) is reproducible under identical operating conditions and, as the basic physical principles of GC are well-established (Ettre and Hinshaw, 1993; Hinshaw and Ettre, 1993) the behaviour of analytes can be predicted for different operating conditions. The retention time of a compound can be a good guide to its identity by reference to known standards.
The basic design of the gas chromatograph can be fitted with a range of specific injectors, columns and detectors to optimize the separation of components and aid their identification. Recent developments in computer control, the use of robotic autosamplers and the trend to couple instruments together for sequential procedures have lead to increased automation for routine analytical tasks performed by GCs in research, factory and quality control environments.