An Evaluation of Five Methods for the Quantitative Determination of Cyclopropenoid Fatty Acids

Abstract

Abstract An evaluation of 5 methods for determining 5% or less cyclopropenoid fatty acids was made in terms of accuracy, precision, and sensitivity. GLC of the methyl mercaptan derivatives of cyclopropenoid fatty acids and titration with hydrobromic acid in toluene were found to be unsuitable. GLC of the silver nitratemethanol derivatives (quantitation by an internal standard) and titration with hydrobromic acid in acetic acid were equally precise, and the former required less sample; however, both methods gave low recoveries. GLC of silver nitrate-methanol derivatives (quantitation by peak area normalization) and a hydrobromic acid-benzene back-titration method gave good recoveries. The Halphen test was found to be the best general method when calibrated with a cyclopropenoid fatty acid standard analyzed by the silver nitrate-methanol GLC method (quantitation by peak area normalization) or the hydrobromic acid-benzene back-titration method.