2.10. Determination of fatty acid composition
Methylation of fatty acids was carried out by the method of Garcés
and Mancha (1993). The fatty acids were identified by comparison
of the retention times of the signals with those of authentic
fatty acid methyl ester standards. A gas chromatograph (Finnigan
Trace; Thermo Fisher Scientific Inc., Waltham, MA) equipped with
capillary column RtxR- WAX (Crossbond with PEG, 30 m
0.32 mm 0.25 lm; Thames Restek UK Ltd, Saunderton, UK) and
flame ionisation detector (FID) was used for this analysis. The
injector and detector temperatures were 230 C and 250 C, respectively.
The carrier gas was helium at 30 kPa in constant pressure
mode, and analyses were performed in split mode (split ratio
100:1). The sample (0.4 ll) was injected into the GC system. A temperature
programme of 130 C (3 min), 130–210 C at 45C/min,
and 210 C (12 min) was used.