An effective GC method for the determination of the fatty acid composition in silkworm pupae oil using a two-step methylation process

In the search for an accurate and effective method for the determination of the fatty acid composition in silkworm pupae oils, five methylation methods were evaluated for use in the gas chromatographic (GC) quantification of fatty acid methyl esters (FAMEs). These included two one-step acid-catalyzed (H2SO4 and BF3) and two one-step base-catalyzed (KOH and NaOCH3) esterification processes, as well as a two-step procedure catalyzed successively by KOH and H2SO4. These methods were comparatively adopted to quantify FAMEs in silkworm pupae oil using GC MS and GC and then their precision, stability and average recovery rates were validated. The results indicated that compared with the four one-step methyl esterification methods, the two-step methylation effectively improved the synthesis yield of FAMEs, conserved the agents and eliminated the usage of potential harmful reagents. The proposed GC method was validated, exhibited good accuracy and precision, and was successfully applied to the quantification of FAMEs in several varieties of silkworm pupae oils. The short analytical run time leads to low costs and a fast chromatographic procedure. In summary, two-step pretreatment had superior performance, providing technical references for the determination and analysis of fatty acids in other oils.