Analysis of Genetically Modified Canola Varieties by Atmospheric Pressure Chemical Ionization Mass Spectrometric and Flame Ionization Detection

Abstract

Canola oil triacylglycerols from genetically modified canola lines were conclusively identified by reverse phase HPLC coupled with atmospheric pressure chemical ionization mass spectrometric (APCI-MS) detection. APCI-MS is a soft ionization technique, which gave simple spectra for triacylglycerols. Spectral identification of the triacylglycerols was based on the diacylglycerol fragments and on the protonated molecular ion [M+H]⁺, except trisaturates which gave no [M+H]⁺. Triacylglycerols were identified and quantitated in normal, high stearic acid and high lauric acid canola varieties by the RP-HPLC/APCI-MS technique. The LC/APCI-MS identification of canola oil triacylglycerols allowed their quantitation by reverse phase HPLC coupled with a commercial flame ionization detector (FID). There was agreement between fatty acid composition obtained by LC/APCI-MS and LC-FID. However, the triacylglycerol resolution obtained by LC/APCI-MS, was superior to LC-FID in the qualitative identification of triacylglycerols present in amounts even below one percent. The oils of the modified canola varieties, compared to typical canola oil, contained increased content of triacylglycerols known to be more oxidatively stable like stearoyloleoyllinoleoyl, distearoyllinoleoyl, stearoyldioleoyl and distearoyloleoyl glycerols in high stearic acid canola oil and dilauroyllinoleoyl, dilauroyloleoyl and lauroyldioleoyl glycerols in high Iauric acid canola oil. These oils contained fewer linolenate-containing triacylglycerols known to decrease oxidative stability. The LC/APCI-MS technique gave better resolution of, and quantitation of triacylglycerols in the canola oils, than the LC/FID. However, the LC/FID system gave satisfactory analyses suitable for many research programs, like the development of genetically modified canola varieties with oils of improved oxidative stability.