Comparison of dodecoxycarbonylvaline microemulsion, solvent-modified micellar and micellar pseudostationary phases for the chiral analysis of pharmaceutical compounds

A direct comparison of dodecoxycarbonylvaline (DDCV) microemulsion, micellar and butanol-modified micellar aggregate systems was performed employing both 2 and 4% DDCV. With respect to either DDCV concentration, use of the micellar system provided the largest elution range, followed by the butanol-modified micellar system and ultimately the microemulsion. Using 2% DDCV, all three aggregate analyses yielded similar values for enantioselectivity, resolution and retention factors that were slightly better using the micellar phase, but efficiencies were consistently better using either the microemulsion or butanol-modified micellar phases. Largely, the microemulsion and butanol-modified micellar phases behaved fairly similar, although use of the butanol-modified micelle provided resolution and efficiency that were slightly better for all but two of the compounds. While reasonable separations were achieved using 2% DDCV, the results using 4% DDCV for the microemulsion system were far superior. Analyses using analogous micellar and butanol-modified micellar aggregates were unstable, making them unsuitable for use at that surfactant concentration.