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HPLC semi‐preparative separation of diclazuril enantiomers and racemization in solution
Author(s) -
Huang Zhan,
Guo Dong,
Fan Jun,
Zhong Yujing,
Zhang Meiyu,
He Limin,
Zhang Weiguang
Publication year - 2020
Publication title -
journal of separation science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.72
H-Index - 102
eISSN - 1615-9314
pISSN - 1615-9306
DOI - 10.1002/jssc.201901201
Subject(s) - racemization , enantiomer , chemistry , chromatography , high performance liquid chromatography , triethylamine , organic chemistry
Diclazuril has been widely used in poultry feed for prevention and treatment of coccidiosis, and its chiral separation is rarely reported. Herein, semi‐preparative separation method of diclazuril enantiomers has been developed through normal‐phase high‐performance liquid chromatography. Effects of chiral stationary phases, alcoholic modifiers, and column temperature on separation of diclazuril were discussed in detail. Both the single‐urea‐bound 4‐chlorophenylcarbamoylated β‐cyclodextrin and amylose tris(3,5‐dimethylphenylcarbamate)‐coated chiral stationary phases showed strong ability in separation of diclazuril by using n ‐hexane–trifluoroacetic acid–ethanol. Then, semi‐preparative separation of diclazuril was carried out through stacked injection, and the "enantiomeric excess" purities of two fractions were over 98%. Next, the electronic circular dichroism profiles of these two fractions in ethanol solution displayed the mirror image of each other in the range 360–200 nm. Moreover, effects of acidic/basic additive, time, and temperature on racemization of diclazuril enantiomers in ethanol solution have been studied in detail through normal‐phase high‐performance liquid chromatography. Racemization of diclazuril enantiomers was remarkably accelerated through adding triethylamine at high temperature. We envision that this systematic investigation of diclazuril at an enantiomeric level would provide valuable information in future studies involving enantioselective bioactive, metabolic, and toxicological activities.