Gas chromatography in food analysis: an introduction

Introduces gas chromatography (GC) a key analytical technique in the food industry. It enables complex organic substances to be separated and identified quickly and cheaply. Substances to be analysed by GC must be volatile, i.e. readily pass into the gas phase. The substance to be analysed is vaporized and moved through a long column by an inert carrier gas. The column is filled with a packing material covered with an involatile liquid. The molecules of each substance in a mixture will become distributed between the gas and the liquid. The more volatile a substance the longer it will be moving with the carrier gas, and the quicker it will emerge from the column. Some substances must be extracted from the food analysis by GC, e.g. fatty acids from triglycerides. Others, such as alcohols, can be injected directly into the column.