Chiral Separations in Nonaqueous Media - Chiral Separations by Capillary Electrophoresis - page 271

10 Chiral Separations in

Nonaqueous Media

Ylva Hedeland and Curt Pettersson

CONTENTS
10.1 Introduction ................................................................................................. 271
10.2 Organic Solvents and Electrolytes Used in Chiral NACE .......................... 277
10.3 Ion-Pair Selectors ........................................................................................ 281
10.3.1 Electrolytes and Solvents in Chiral Ion-Pair Selector Systems ..... 286
10.3.2 Pharmaceutical Applications of Ion-Pair Selectors ....................... 289
10.4 Cyclodextrins .............................................................................................. 290
10.4.1 Applications Using CDs Derivatives ............................................. 297
10.5 Miscellaneous Chiral Selectors Used in NACE.......................................... 298
10.6 Improvement of Detection Limit in Chiral NACE ..................................... 299
10.7 Concluding Remarks...................................................................................304
List of Abbreviations..............................................................................................304
References .............................................................................................................. 306

10.1 INTRODUCTION
The use of nonaqueous solvents in capillary electrophoresis (CE) was introduced in
1984 by Walbroehl and Jorgensen [1]. One year later, the i rst chiral separation in aque-
ous CE was published by Gassmann et al. [2]. However, little or almost no attention
was paid to the nonaqueous media in CE until the middle of the 1990s and the i rst
application of chiral separation in a nonaqueous medium was presented as recently
as 1996 [3-6]. Since then, approximately 50 articles concerning enantioseparations
in nonaqueous capillary electrophoresis (NACE) have been published, and over 40
different chiral selectors have been described. This chapter covers articles published
during the years 1996-2007. For reviews on chiral separation in CE and NACE,
see the Refs. [7-13].
In CE, nonaqueous separation can be used as a complement to aqueous separation
since it facilitates the use of chiral selectors with a low solubility in water [4,6,14].
Furthermore, it may improve the enantioseparation for selectors with a lack of or low
enantioselectivity in aqueous buffers [15]. Another advantage of NACE is that the
use of organic solvents enables poorly water-soluble substances to be analyzed [16].
The enhanced solubility of nonpolar substances is advantageous when injection of
high concentrations is necessary to lower the limit of detection (LOD), e.g., for chiral

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