Chiral separation of six triazole fungicides by supercritical fluid chromatography

The enantiomeric separation of six triazole fungicides (diclobutrazol, bitertanol, metconazole, etaconazole, bromuconazole and difenoconazole) on the Chiralcel OD-H column by supercritical fluid chromatography, using supercritical carbon dioxide as the mobile phase, was investigated. The influences of pressure (13-17 MPa), modifiers (methanol, ethanol and 2-propanol) and their contents in the mobile phase (0-15%,V/V) on the separation of enantiomers were evaluated. The results were compared with those obtained on Sino-Chiral OJ and Chiralpak IB column. The results showed that the retention times of six triazole fungicides were longer than 60 min under pure CO2 and it could be reduced to less than 40 min when adding organic modifiers. The enantioseparations of diclobutrazol, bitertanol, metconazole and bromuconazole were achieved within 20 min at 34 ℃, 15 MPa at a flow-rate of 2 mL/min. Their optimal concentrations of modifiers were 3% (V/V) ethanol, 13% (V/V) ethanol, 6% (V/V) methanol and 7% (V/V) ethanol. The Chiralcel OD-H column demonstrated a better enantiomeric separation capacity and a 10-20 min's longer retention time for the triazole fungicides.