Gas Chromatography - Applications > Food and Beverage Products > Page 71

Food and Beverage Products

Due to the likely contamination of food and beverage products with pesticides, herbicides and many other materials that are considered a health risk, all such products on sale today must be carefully assayed. There is extensive legislation controlling the quality of all human foods and drinks, and offensives carry very serious penalties. In addition, the condition of the food is also of great concern to the food chemist, who will look for those trace materials that have been established to indicate the onset of bacterial action, aging, rancidity or decomposition. In addition, tests that identify the area or country in which the food was processed or grown may also be needed. The source of many plants (herbs and spices) can often be identified from the peak pattern of the chromatograms obtained directly from headspace analysis. Similarly, unique qualitative and quantitative patterns from a GC analysis will often help identify the source of many alcoholic beverages.

Unfortunately, food analysis involves the separation and identification of very complex mixtures and the difficulties are compounded by the fact that the components are present at very low concentrations. Thus, gas chromatography is the ideal (if not only) technique that can be used successfully in food and beverage assays and tests.

The potential carcinogenity of the aromatic hydrocarbons make their separation and analysis extremely important in environmental testing. However, the aromatics can pose some serious separation problems (for example, the m- and p-xylenes) due to the closely similar chemical structure and characteristics. The xylene isomers differ in structure (although not optically active) have similar spatial differences to pairs of enantiomers. It follows, chiral stationary phases that separate enantiomers can also be used for separating spatial isomers that are not necessarily optically active. Nevertheless, the separation ratios of such isomeric pairs (even on cyclodextrin stationary phases) is still very small, often in the 1.021.03 range. As a consequence, the use of high efficiency capillary columns is essential, if reasonable analysis times are also to be maintained.