ENANTIOMERIC RESOLUTION ON CHIRAL-AGP WITH THE AID OF EXPERIMENTAL-DESIGN - UNUSUAL EFFECTS OF MOBILE-PHASE PH AND COLUMN TEMPERATURE

Baseline separation of the enantiomers of two structurally related dih ydro-pyranoimidazopyridines was performed within 15 min on Chiral-AGP by using experimental design. The retention times of the enantiomers w ere found to have an optimum at a mobile phase pH of around 7. However , the enantioselectivity increased with increasing mobile phase pH. Be sides the interesting effect of pH, only a minor decrease in the enant ioselectivity was obtained by increasing the column temperature. The v ariables, column temperature, mobile phase pH and concentration of ace tonitrile, influenced all four stereoisomers in the same way. However, the statistical model separated the loadings i.e., the influence of t he descriptor variables on the capacity factors of the first and last eluted enantiomers of the two solutes investigated, which indicated di fferences in retention mechanisms.