The gas chromatography-flame ionization detector (GC-FID) chromatogram was used to determine the relative concentration, using the peak areas, on Agilent system 5975C, of which analysis method was similar to that shown for the
GC–MS system above. Phenyl-methylpolysiloxane – 5% capillary column (30m 0.25mm di, 0.25m film; J & W Scientific, Folsom, CA, USA). Hydrogen was used as carrier gas.