2.4.2. Fatty acid composition of FOG
Its composition of free and esterified fatty acids was determined
according to the methods described in AOAC 996.06 (AOAC, 2000).
Dried FOG was dissolved in chloroform/diethyl ether (1:1, by volume)
and treated with BF3/methanol. A Supelco capillary column
(100 m 0.25 mm) fitted to an Agilent Gas Chromatograph
(6890N) was used. The carrier gas was He with a split ratio of
100. The injector and the flame ionisation detector temperatures
were 250 C. The temperature of the oven was varied according
to the following programme. After application of the solution of
methyl esters (1 ll), the temperature of the oven was held at
140 C for 5 min. Then it was increased at the rate of 3 C/min until
250 C was reached and this temperature was maintained for
17 min. The system was calibrated by application of Supelco™ 37
Component Fatty Acid Methyl Ester Mix.