Methyl esters from the copepod Tisbe biminiensis assayed by two transesterification methods

Abstract

The present study assessed the efficiency of two transesterification methods for the identification of fatty acids in the copepodTisbe biminiensisVolkmann-Rocco, 1973. In the first method, the samples were esterified by basic catalysis with KOH in methanol, and in the second method they were esterified by acid catalysis with BF3. Fatty acids were identified by comparison of retention times and co-injection with standard Mix C4-C24, using gas chromatography and gas chromatography-mass spectrometry. Twenty-nine fatty acids were detected in samples transesterified by basic catalysis or acid catalysis. The predominant fatty acids were C18 (19.18%), C16 (13.02%), and C12 (11.39%) for samples transesterified by acid catalysis; and C13 (25.24%), C21 (11.32%), and C18 (10.65%) for samples transesterified by basic catalysis. The results show that fatty acid analysis for copepods may be affected by the transesterification method. Sample transesterification by acid catalysis was efficient to identify monosaturated and polyunsaturated fatty acids, whereas transesterification by basic catalysis was efficient to identify saturated fatty acids. Essential fatty acids were present in the copepod, which suggests thatT.biminiensisis a useful food to be used in larviculture.