Retention behavior of triglycerides in octadecyl packed subcritical fluid chromatography with CO2/modified mobile phases

A study of the retention behavior of vegetable oil triglycerides was carrie d out in subcritical fluid chromatography (SubFC) with CO2/modifier mobile phases. Analyses of 15 oils have enabled us to set up a retention diagram w hich includes similar to 30 triglycerides. This diagram establishes a relat ion between triglyceride series retention and their unsaturation number. Fu rthermore, another relationship between retention and the triglyceride carb on number was studied. The retention properties were identical with those r eported in nonaqueous reversed-phase liquid chromatography or in SubFC with neat CO2: the Linearity of these relationships and retention order that fo llows the partition number. Moreover, specific effects of modifier on these relationships or on retention variations were observed. Using octadecyl pa cked columns, these particular behaviors underline that the compound solubi lity is different between modified subcritical phases and nonaqueous liquid phases. Finally, these behaviors can be useful to increase the triglycerid e separation and the previous relationships can be applied to improve the i dentification of unknown triglycerides.