Precision and accuracy in gas liquid chromatography of C14‐C18 fatty methyl esters

Abstract

AbstractRepetitive analyses of four primary standards for fatty methyl esters by gas liquid chromatography (GLC) with polyester columns and thermal conductivity detection established standard deviations ranging from ŷ0.3舑0.5% corresponding to coefficients of variation of 1.0舑2.0%. These data, representing a relative error of measurement of 1.5舑3.0% at a 99% confidence level, suggest a precision approaching that of conventional spectrophotometric measurements.Proportionality factors, calculated from known mass or molar concentration divided by area % from GLC analysis, were found to be reproducible erratum factors which may be generally applicable to GLC analysis of fatty methyl esters with polyester columns and thermal conductivity detectors.Mass response to a thermal conductivity detector was found to decrease with either increasing molecular weight for saturated C14舑C18 fatty methyl esters or with unsaturation among the C18 unsaturated esters, while molar response increases with molecular weight and decreases with degree of unsaturation.The use of uncorrected area % data can introduce significant absolute mass errors ranging from about +11% for myristic acid to 蜢17% for linolenic acid.