Materials
Biodiesel samples were acquired from the following sources: 1) CaME was
from Archer Daniels Midland (Decatur, IL, USA); 2) PME produced by Sime
Darby Biodiesel Sdn. Bhd. (Selanger, Malaysia) with assistance from the
Malaysian Palm Oil Board (Washington, DC, USA); and 3) SME was from Ag
Environmental Products (Lenexa, KS, USA). According to the fuel
producers, these biodiesel samples were not treated with performance
enhancing additives including antioxidants. Fatty acid concentration
profiles for these biodiesel fuels are presented in Table S1 in
the supporting information.
Pure MeC18:1 (99.5 ± 0.1 % 9(Z)-octadecenoic acid methyl ester) and
MeC18:2 (99.0 ± 0.1 % 9(Z),12(Z)-octadecadienoic acid methyl ester)
were supplied by Nu Chek Prep (Elysian, MN, USA). The purities of
MeC18:1 and MeC18:2 were verified by analysis with a PerkinElmer
(Waltham, MA, USA) Clarus 500 gas chromatograph (GC) with a flame
ionization detector (FID) using an HP-88 column (30 m x 0.250 mm x 0.20
μm) from Agilent (Santa Clara, CA, USA). The carrier gas was hydrogen
and injector and detector temperatures were 240 °C and 280 °C. The
temperature program was: 1) hold at 100 °C for 5 min; 2) ramp at 10 °C
min−1 to 220 °C; 3) hold at 220 °C for 15 min. Three
replicate analyses were performed and results for the pure FAME were
reported as average values.