From multimodal liquid chromatography to supercritical fluid chromatography: Mapping chiral separation of the major organic ultraviolet filters

Abstract

The widespread presence of chiral organic UV filters in the environment raises critical concerns due to their potential enantioselective toxicity and persistence. This study provides the first comprehensive enantioseparation screening of five such compounds – enzacamene, homosalate, octinoxate, octisalate, and octocrylene – using multimodal liquid chromatography (LC), as well as supercritical fluid chromatography (SFC) with 20 polysaccharide-based chiral stationary phases (CSPs). Enzacamene and homosalate were baseline-resolved across all tested conditions, including SFC, while octisalate showed separation in normal and reversed-phase modes. Octinoxate was resolved only in normal-phase mode, and octocrylene was not fully resolved, though near-baseline separation was achieved in polar organic and normal-phase modes. SFC, particularly with non-conventional CO₂/hexane–ethanol eluent, proved complementary to LC, achieving comparable or superior enantioresolution. Coated amylose columns demonstrated superior performance in reversed-phase mode, whereas immobilized CSPs, particularly chloromethylphenylcarbamate-based selectors, displayed broader applicability across multiple mobile phase systems. These findings emphasize the necessity of multimodal approaches to optimize the enantioseparation of highly lipophilic environmental contaminants and establish a robust analytical foundation for future ecotoxicological and regulatory studies.