columnsDuring this study, some comparisons were made with twocommercially available GC columns. The first column had a non-polar 95% methyl/5% phenyl polysiloxane stationary phase (1 mthick × 0.53 mm I.D. × 30 m long; model EC-5; Alltech, Deerfield, IL,USA). The other had a polar polyethylene glycol stationary phase(1 m thick × 0.53 mm I.D. × 30 m long; model Stabilwax Cross-bond Carbowax; Chromatographic Specialties). A standard HP 5890Series 2 GC-FID instrument was used for these comparative columnseparations.