Enantiomeric Separation and Detection of 2-Arylpropionic Acids Derivatized with [(N,N-Dimethylamino)sulfonyl]benzofurazan Reagents on a Modified Cellulose Stationary Phase by High-Performance Liquid Chromatography

Abstract

(RS)-2-Arylpropionic acids (2-APAs) were derivatized with the fluorogenic reagents, 4-[(N,N-dimethylamino)sulfonyl]-7-piperazino-2,1,3-benzoxadiazole (DBD-PZ) and 4-[[(N-hydrazinoformyl)methyl]-N-methyl]amino-7-[N,N-(dimethylamino)sulfonyl]-2,1,3-benzoxadiazole (DBD-COHz), and their enantiomeric separation by a chiral stationary phase high-performance liquid chromatography was investigated in the reversed-phase mode with H(2)O/CH(3)CN or H(2)O/MeOH as the mobile phase on a column of cellulose tris(3,5-dimethylphenyl carbamate) coated on a silica gel support (Chiralcel OD-R). The derivatives with DBD-PZ were enantiomerically separated well under the elution condition of H(2)O/MeOH, based on the π-π interaction between the derivatives and the stationary phase. The rigid and bulky structure of DBD-PZ was demonstrated to be more effective as compared to the less rigid ones. The derivatives with DBD-COHz were more efficiently separated into each enantiomer with H(2)O/CH(3)CN as the eluent. The effective separation was based on hydrogen-bonding interaction between the acid hydrazide of the derivatives and the carbamoyl moiety of the stationary phase. There was a reversal in the elution order of the enantiomers between the two fluorescent derivatives. The detection limits obtained for each enantiomer were approximately 10-30 fmol on column. The derivatization with the reagent and the concomitant use of the reversed-phase and chiral stationary-phase HPLC were demonstrated to be useful for the enantiomeric quantification in rat plasma after intravenous administration of flurbiprofen racemate, a representative of 2-APAs.