Enantiomeric separations of chiral polychlorinated biphenyls on three polysaccharide-type chiral stationary phases by supercritical fluid chromatography

Enantiomeric separations of 18 chiral polychlorinated biphenyls (PCBs) were investigated on three polysaccharide-type chiral stationary phases (CSPs; Sino-Chiral OJ, Chiralpak IB, and Chiralcel OD) by supercritical fluid chromatography (SFC). With these commonly used polysaccharide CSPs, 17 PCBs except PCB 135 (RS = 0.81) were well resolved (RS > 1.5) under appropriate mobile phases and temperatures. Using Sino-Chiral OJ, 14 PCBs could be baseline-separated, while only one and nine PCBs could be completely separated using Chiralpak IB and Chiralcel OD, respectively. The influence of column temperature was studied for the optimization of resolution, as well as for the type and percentage of organic modifier in the mobile phase. The resolution decreased as the temperature increased in the range of 26–40 °C in which the enantiomeric separations were an enthalpy-driven process. The addition of modifiers in the mobile phase decreased the resolution of the PCB enantiomers, but it clearly shortened their retention time. These separation results indicate that SFC is a promising chromatographic technique for chiral separation and enantiopure standard preparation.