2.5 Quantification of total fatty acid methyl esters (FAMEs)
A modified Bligh-dyer technique was adapted from shaikh et al[35] for extracting
total fatty acid methyl esters (FAMEs). The hexane layer was injected
into an Agilent 6890 gas chromatograph (GC) instrument, which was
connected to a triple quadrupole outfitted with an OMEGAWAX 250 column
(30 m x 0.25 m x 0.25 m). The GC-MS running conditions were as stated by
Kareya et al [47].
Concisely, 2 L of the sample was run in the split mode (1:10) for 25
minutes, with the beginning oven temperature set at 150 °C and a
simultaneous escalation of 10 °C min-1 to 240 °C. For
quenching, helium (He) and nitrogen (N2) gas were
employed at flow rates of 2.25 mL min-1 and 1.5 mL
min-1, respectively. The data was collected using the
Agilent 7000D triple quadrupole selective mass detector, which has a
scan range of 30 to 550 amu. The produced peaks were compared to NIST
libraries for identification and alignment based on retention indices as
well as mass spectral similarity (cut-off hits with R-values greater
than 600 were selected).