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Headspace in gas chromatography and GC vial for sale
Dec. 30th, 2019
Headspace GC is a sampling technique that involves the indirect determination of volatile components in liquid or solid samples by analyzing the gas phase in which the sample in the closed system is in a thermodynamic equilibrium.
It is mainly used to determine volatile components in trace amounts. Traditional extraction and enrichment procedures (such as solvent extraction, steam distillation, and vacuum distillation) have inherent disadvantages in co-extracting components from the matrix and introducing excess compounds from the extraction medium. On the other hand, headspace analysis must provide an extract that is limited to volatile components that are well-suited for GC.
The volatile nature of the headspace sample reduces the need for cleaning and maintenance of the injector, column, and detector, and saves instrument downtime. Examples of particularly useful headspace analysis include identifying migrating contaminants and volatile substances in packaging and food, determining pesticide residues, and analyzing flavor and drinking water.
The classification of headspace techniques is so extensive and diverse that any attempt at classification is incomplete. According to the method of extracting volatiles, there are two methods of static and dynamic to distinguish headspace. Dynamic method include a variety of techniques, called strip-trap and purge, gas phase stripping analysis and purge and trap. With static methods, the sample and vapor are balanced in a closed container and the headspace is manually or automatically sampled by a syringe. In either case, gaseous effluents of gas usually go through suitable capture media, such as cold traps, activated carbon or porous polymers; then put into the gas chromatography. This approach provides a concentration effect by which sensitivity is increased.