Comprehensive two-dimensional liquid chromatography with ultraviolet, evaporative light scattering and mass spectrometric detection of triacylglycerols in corn oil
2008
van der Klift, Elbert J.C. | Vivó-Truyols, Gabriel | Claassen, Frank W. | van Holthoon, Frederique L. | van Beek, Teris A.
An improved comprehensive two-dimensional (LCxLC) HPLC system for the analysis of triacylglycerols was developed. In the first-dimension, a Ag(I)-coated cation exchanger (250mmx2.1mm, 5μm) was employed with a gradient from 100% MeOH to 6% MeCN in MeOH at 20μL/min. Using a 10-way valve with two switching loops, 1min sections of the first-dimension were introduced in the second-dimension consisting of a 30mmx4.6mm C18 (1.8μm) column with an isocratic mobile phase of methanol-methyl tert-butyl ether (70:30) at 3.0mL/min. As the second-dimension solvent was stronger than the first-dimension solvent, focusing in the second-dimension took place, leading to better separations than in previously reported analyses in which hexane was the main constituent of the first-dimension eluent. Compounds differing by 2 in their partition number were baseline separated in the second-dimension. Detection took place by UV at 210nm, evaporative light scattering and (+)-atmospheric pressure chemical ionisation-MS with the latter giving the best results. Corn oil was investigated and 44 compounds could be detected: 34 triacylglycerols (TAGs), 8 oxygenated TAGs, and 2 TAGs containing a trans double bond. Data manipulation allowed the construction of contour plots and the automated calculation of the first- and second-dimension retention times and peak areas. Quantitative results are compared with a fatty acid methyl ester analysis, and with literature data.
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