Isolation of volatile compounds for glc analysis.

Jennings, W.G., Wohleb, R.H. and Lewis, M.J.

Abstract
The use of Porapak traps to isolate the volatile compounds from beer is described. The gas used for sampling is purified by passing it through traps of molecular sieve (13X and 5A), the Porapak traps are first purged with purified gas for 3 days at 150 degrees C and are then stored under a small continuous flow of purified gas. Volatiles are trapped at 38 degrees C for 1 h, developed for 10 min and the essence recovered by backflushing for 1 h at 100 degrees C. This sampling procedure has allowed separation of over 100 headspace volatiles instead of the normal 8 to 10 and examples of the chromatograms obtained are given. The column used is a coiled glass capillary column and the method of coating it is described. An inlet splitter made of glass has been designed and patented which gives improved results.
Keywords: beer gas chromatography isolation volatile compound