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Optimization of the enantioseparation of a diaryl‐pyrazole sulfonamide derivative by capillary electrophoresis in a dual CD mode using experimental design
Author(s) -
RogezFlorent Tiphaine,
Foulon Catherine,
Six Perrine,
Goossens Laurence,
Danel Cécile,
Goossens JeanFrançois
Publication year - 2014
Publication title -
electrophoresis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.666
H-Index - 158
eISSN - 1522-2683
pISSN - 0173-0835
DOI - 10.1002/elps.201300639
Subject(s) - repeatability , capillary electrophoresis , chemistry , chromatography , analyte , cationic polymerization , central composite design , coating , methanol , enantiomer , polymer , capillary action , materials science , response surface methodology , polymer chemistry , organic chemistry , composite material
A CE method using dual cationic and neutral cyclodextrins ( CD ) was optimized for the enantiomeric separation of a compound presenting a diaryl sulfonamide group. Preliminary studies were made to select the optimal CD s and pH of the BGE . Two CD s (amino‐β‐ CD and β‐ CD ) were selected to separate the enantiomers in a 67 mM phosphate buffer at pH 7.4. However, the repeatability of the analyses obtained on bare‐fused silica capillary was not acceptable owing to the adsorption of the amino‐β‐ CD to the capillary. To prevent this, a dynamic coating of the capillary was used employing five layers of ionic‐polymer (poly(diallyldimethylammonium) chloride ( PDADMAC ) and poly(sodium 4‐styrenesulfonate). The efficiency of the coating was assessed by measuring the EOF stability. Repeatability of the injections was obtained when intermediate coating with PDADMAC was performed between each run. Secondly, this enantioseparation method was optimized using a central composite circumscribed design including three factors: amino‐β‐ CD and β‐ CD concentrations and the percentage of methanol. Under the optimal conditions (i.e. 16.6 mM of amino‐β‐ CD , 2.6 mM of β‐ CD , 0% MeOH in 67 mM phosphate buffer (pH 7.4) as BGE , cathodic injection 0.5 psi, 5 s, separation voltage 15 kV and a temperature of 15°C), complete enantioresolution of the analyte was obtained. It is worth mentioning that the design of experiments ( DOE ) protocol employed showed a significant interaction between CD s, highlighting the utility of DOE in method development. Finally, small variations in the ionic‐polymer concentrations did not significantly influence the EOF , confirming the robustness of the coating method.