Topics - Headspace
The technique of headspace analysis is often used to determine contaminants in air when in equilibrium with different types of materials. The deterioration of certain foods is accompanied by the characteristic generation of low molecular weight organic acids, aldehydes and ketones. Consequently, an analysis of the air above, and in equilibrium with the food could identify spoiling, and in fact, determine the extent to which the food had deteriorated. A quite different application would be to identify the components contributing to the fragrance of a flower by analyzing the air that surrounds it. The procedure is to place the material of interest in a flask fitted with a serum cap and the sample given time to become in equilibrium with the air in side the flask. A sample of air is then removed from the flask by drawing the air through a tube containing and adsorbent (usually a reversed phase packing) by means of a syringe. The material is then desorbed from the adsorbent by a suitable solvent such as methanol or acetonitrile and a sample of the displacement liquid injected onto a GC or LC column. This technique has a wide range of applications, food contamination, pollution, fragrance analysis and toxicity studies are just a few of those to which the technique has been applied.