Separation of racemic mixtures of sn-1(3)-monoacylglycerols by enantioselective-HPLC/ELSD

Enantiomeric separations were performed on five modified polysaccharide-based chiral stationary phases (CSPs) containing cellulose tris(3,5-dimethylphenylcarbamate) (Lux Cellulose-1), cellulose tris(3-chloro-4-methylphenylcarbamate) (Lux Cellulose-2), cellulose tris(4-methylbenzoate) (Lux Cellulose-3), cellulose tris(4-chloro-3-methylphenylcarbamate) (Lux Cellulose-4), amylose tris(5-chloro-2-methylphenylcarbamate) (Lux Amylose-2) by high-performance liquid chromatography and evaporative light scattering detector. A method for direct separation of pairs of sn-1(3)-monoacylglycerols (MAGs) was established using n-hexane/2-propanol as the mobile phase. The washing of CSPs with mobile phases based on n-hexane/2-propanol, containing small amount of acids, improved considerably the efficiency of separations. Racemic mixtures of sn-1(3)-MAGs with different acyl chains could not be directly separated using only one of the columns tested; employing a tandem column system that consisted of a very short silver-loaded column connected downstream with Lux Cellulose-1 the method allowed, for the first time, the separation of four enantiomeric pairs of standard in a single chromatographic run.