Evaluation of a methylation procedure to determine cyclopropenoids fatty acids from Sterculia striata St. Hil. Et Nauds seed oil

Cyclopropenoids fatty acids (CPFA) from Sterculia striata seed oil were characterized by gas chromatography/mass spectrometry (GC/MS) and quantified by gas chromatography-flame ionization detector (GC-FID) after derivation to fatty acid methyl esters using a cold base-catalyzed procedure. 1H nuclear magnetic resonance (NMR) analysis were done in oil and fatty acid methyl esters derivatives to quantify CPFA and verify artifacts formation during the base-catalyzed reaction. Similar quantities of CPFA were found in S. striata and Sterculia foetida seed oils before and after a base-catalyzed methylation by NMR analysis, with no artifact formation. These results were compatible with those obtained by GC-FID analysis. Transmethylation with KOH in methanol was an appropriated method to prepare cyclopropenoids fatty acids methyl esters and quantify them by GC and NMR analysis.