Gas Chromatography - Applications > Food and Beverage Products > Page 72


Courtesy of Supelco Inc.


Figure 46 The Separation of Some Aromatic Hydrocarbons

The separation of some aromatics contained in a mixture of hydrocarbons is shown in figure 46. A column 30 m long, 0.25 mm I.D., carrying a film of permethylated b-cyclodextrin 0.25 mm thick, was used by Supelco for the separation. The column was operated isothermally at 50˚C and helium was use as the carrier gas at a flow velocity of 20 cm/s. It is seen that baseline separation is achieved for the m- and p-xylenes and that the separation ratio for the two isomers was about 1.03.

Chiral analysis in the drug industry is now extremely crucial. There are two factors that have contributed to the importance of chiral GC in drug analysis. Firstly, the critical nature of the enantiomeric character of a drug has now been well established (largely arising from the thalamide disaster). The Food and Drug Administration, as a consequence, has mandated that the physiological effect of both or all enantiomers of any drug that can exist in chiral form must be determined. Moreover, the chiral purity of any commercially available drug must also be monitored and controlled. GC is a natural technique for this type of work as many modern drugs have relatively small molecular weights and consequently are volatile or can easily be made into volatile derivatives. In addition, GC capillary columns can easily provide the high efficiencies necessary to separate very similar compounds with relatively small separation ratios.