Chromatographic separation of chlorthalidone enantiomers using beta-cyclodextrins as chiral additives.
Different beta-cyclodextrins have been tested as chiral additives in the mobile phase for the chromatographic analysis of chlorthalidone enantiomers in a C18 LiChrospher (125 x 4 mm I.D.) column. The effect on enantioresolution of different parameters was studied: composition of the mobile phase (percentage of organic solvent, type of buffer and pH), mobile phase flow-rate, and type and concentration of beta-cyclodextrin. A 25:75 mixture of methanol and 0.1 M phosphate buffer, pH 4, containing 2% triethylamine (v/v), and 12.5 mM beta-cyclodextrin, at a flow-rate of 0.8 ml/min, was found to be the best option for the resolution of chlorthalidone enantiomers. Under such conditions, linear calibration curves were obtained in the 0.5-20-microg/ml interval using UV detection at 230 nm. The limit of detection for both isomers was 50 ng/ml. The utility of the described assay has been tested by analyzing chlorthalidone in different pharmaceutical preparations. Examples of application to biological samples are also given.
Herráez-Hernández
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R
Department of Analytical Chemistry, University of Valencia, Spain.
Campíns-Falcó
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P
D002752:Chlorthalidone / Q000097:blood / Q000302:isolation & purification* / Q000652:urine; D003505:Cyclodextrins / Q000737:chemistry*; D004232:Diuretics / Q000097:blood / Q000302:isolation & purification* / Q000652:urine; D006801:Humans; D007202:Indicators and Reagents; D012996:Solutions; D012997:Solvents; D013056:Spectrophotometry, Ultraviolet; D013237:Stereoisomerism; D047392:beta-Cyclodextrins
D003505:Cyclodextrins; D004232:Diuretics; D007202:Indicators and Reagents; D012996:Solutions; D012997:Solvents; D047392:beta-Cyclodextrins; C031215:betadex; D002752:Chlorthalidone