Identification of monoacyl- and monoalkylglycerols by gas–liquid chromatography–mass spectrometry using polar siloxane liquid phases

Abstract

A comparative study was made of the spectra obtained after gas–liquid chromatography–mass spectrometry of the trimethylsilyl ethers of 1- and 2-monoacyl- and monoalkylglycerols. The glycerol derivatives were resolved on the basis of positional substitution and the degree of unsaturation on Silar-5CP (a cyanopropylphenylsiloxane) liquid phase, and the peaks were examined in a Varian MAT CH-5 single-focusing mass spectrometer. The 1-monoacyl- and 1-monoalkylglycerols possessed m/e M – 103 and m/e 205, respectively, as unique peaks, while the 2-monoacyl- and 2-monoalkylglycerols contained m/e 218 as the highly favored fragment. These differences were large and consistent enough to serve as a basis for identification and quantitation of the isomers in a mixture. The saturated and unsaturated monoacyl- and monoalkylglycerols differed markedly in the kind and intensity of the base peaks and other major fragments. In view of the effective gas–liquid chromatographic resolution of these compounds, the marked differences in the spectra of the trimethylsilyl ethers of the saturated and unsaturated species provided a distinct advantage for their identification by the gas–liquid chromatography–mass spectrometry system.

Keywords

• 1-alk-1-enylglycerols
• cyanopropylphenylsiloxane
• quantitative analysis
• positional isomers
• saturated and unsaturated species
• trimethylsilyl ethers