DIRECT TRANSESTERIFICATION OF TOTAL FATTY-ACIDS OF ADIPOSE-TISSUE, AND OF FREEZE-DRIED MUSCLE AND LIVER WITH BORON-TRIFLUORIDE IN METHANOL

The purpose of this study was to demonstrate direct transesterificatio n of fatty acids of tissue total lipids with boron-trifluoride in meth anol. Adipose tissue, muscle, and liver samples obtained from market-w eight lambs, were transesterified with 14% boron-trifluoride in methan ol at 80 degrees C. Total lipids of additional samples were first solv ent-extracted and then transesterified with 14% boron-trifluoride in m ethanol, Thin layer chromatographic evaluation revealed quantitative c onversion of triacylglycerol- and polar lipid-fatty acids to fatty aci d methyl esters using direct transesterification. No differences in fa tty acid composition were observed for adipose tissue (p > 0.05), howe ver, for muscle, 20:4 was greater (p = 0.01) with direct transesterifi cation. For liver, greater concentrations of fatty acids were observed for the direct transesterification method (p < 0.02). Weight percenta ges of adipose and muscle fatty acids were unchanged from 15 to 180 mi n of direct transesterification; however, 120 and 90 min of direct tra nsesterification were required for adipose tissue and muscle, respecti vely, for complete transesterification. It was concluded that for anal ysis of total fatty acids, one-step direct transesterification with bo ron-trifluoride in methanol is a useful and acceptable procedure. (C) 1997 Elsevier Science Ltd.