Qualitative Analysis of Triglycerides in Cooking Oil Using GC/MS

Introduction

Cooking oil is primarily composed of a mixture of triglycerides, which are three fat acids molecules attached to a glycerol molecule by ester linkages. There are many naturally occurring triglycerides, but few of these are included in commercial mass spectral databases, making the identification of the compounds by library searches difficult. When these compounds are analyzed by electron ionization (EI), the molecular ion is often not detected due to the extensive fragmentation of these compounds. Analysis of the compounds by both EI and chemical ionization (CI) provides significantly more information for positive compound identification. CI dramatically increases the intensity of the molecular ion, and the combination of the molecular weight information from CI, and the fragmentation information from EI enhances positive identification of the triglyceride fatty acid composition. The following examples illustrate the use of the combined data from EI and CI for the triglyceride analysis of a butter sample by GC/MS.

July 2, 2009 GMT