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Enantiomeric separation of some common controlled stimulants by capillary electrophoresis with contactless conductivity detection
Author(s) -
Mantim Thitirat,
Nacapricha Duangjai,
Wilairat Prapin,
Hauser Peter C.
Publication year - 2012
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.201100370
Subject(s) - enantiomer , ephedrine , chemistry , chromatography , pseudoephedrine , capillary electrophoresis , enantiomeric excess , selectivity , cyclodextrin , racemic mixture , chiral derivatizing agent , organic chemistry , chiral column chromatography , enantioselective synthesis , neuroscience , biology , catalysis
CE methods with capacitively coupled contactless conductivity detection (C 4 D) were developed for the enantiomeric separation of the following stimulants: amphetamine (AP), methamphetamine (MA), ephedrine (EP), pseudoephedrine (PE), norephedrine (NE) and norpseudoephedrine (NPE). Acetic acid (pH 2.5 and 2.8) was found to be the optimal background electrolyte for the CE‐C 4 D system. The chiral selectors, carboxymethyl‐β‐cyclodextrin (CMBCD), heptakis(2,6‐di‐ O ‐methyl)‐β‐cyclodextrin (DMBCD) and chiral crown ether (+)‐(18‐crown‐6)‐2,3,11,12‐tetracarboxylic acid (18C6H 4 ), were investigated for their enantioseparation properties in the BGE. The use of either a single or a combination of two chiral selectors was chosen to obtain optimal condition of enantiomeric selectivity. Enantiomeric separation of AP and MA was achieved using the single chiral selector CMBCD and (hydroxypropyl)methyl cellulose (HPMC) as the modifier. A combination of the two chiral selectors, CMBCD and DMBCD and HPMC as the modifier, was required for enantiomeric separation of EP and PE. In addition, a combination of DMBCD and 18C6H 4 was successfully applied for the enantiomeric separation of NE and NPE. The detection limits of the enantiomers were found to be in the range of 2.3–5.7 μmol/L. Good precisions of migration time and peak area were obtained. The developed CE‐C 4 D method was successfully applied to urine samples of athletes for the identification of enantiomers of the detected stimulants.