Separation of multicomponent mixtures of 2,4-dinitrophenyl labelled amino acids and their enantiomers by capillary zone electrophoresis

Abstract

The use of capillary zone electrophoresis (CZE) for the separation of a group of 33 2,4-dinitrophenyl labeled amino acids (DNP-AA), including DNP-AA racemates, DNP-L-AA enantiomers and achiral DNP-AAs, was investigated. Alpha-, beta- and gamma-cyclodextrins (CDs) and their derivatives (hydroxypropyl derivatives of alpha-, beta- and gamma-CDs, polymeric beta-CD and 6A-methylamino-beta-cyclodextrin (MA-beta-CD)) served as complexing agents and chiral selectors in this investigation. Although native alpha- and gamma-CDs and their derivatives influenced the effective mobilities of the studied DNP-AAs in different ways, they generally failed to resolve enantiomers of the individual DNP-AAs. On the other hand, beta-CD and all of its derivatives were found to be effective in this respect. Of these, the best results were achieved with a positively charged MA-beta-CD and this chiral selector resolved enantiomers of ten DNP-AA racemates available for this study. However, a complete resolution of these enantiomers in one CZE run required that the effect of the chiral selector be complemented by complexing effects of polyvinyl pyrrolidone (PVP) or gamma-CD. Complexing and chiral recognition capabilities of MA-beta-CD combined with complexing effects of gamma-CD and PVP provided separating conditions suitable for the CZE separations of multicomponent mixtures of DNP-AAs with preserved resolutions of the enantiomers. For example, a mixture consisting of 43 DNP-AA constituents was resolved using an MA-beta-CD/gamma-CD combination with three peak overlaps.

Microassay for ketamine and metabolites in plasma and serum based on enantioselective capillary electrophoresis with highly sulfated γ-cyclodextrin and electrokinetic analyte injection

“…CE is an important technology for enantioselective analyses, including stereoselective bioanalytical drug and metabolite monitoring [12][13][14][15]. The rather poor concentration sensitivity, however, is an inherent limitation and requires proper attention particularly in regard to the charge of the chiral selector employed [5].…”

Recent progress in capillary electrophoretic analysis of amino acid enantiomers

“…When the charged CDs interact with racemic amino acids, the analytes migrate at a different velocity from a surrounding aqueous phase due to the electrophoretic migration of the ionic CDs. Although various anionic [34][35][36][37][38][39][40][41][42][43] and cationic CDs [44][45][46][47][48][49][50][51][52][53][54][55][56][57][58][59][60][61][62] are synthesized for CDEKC as summarized in Table 2, sulfated CDs (S-CDs) [34,35] and highly sulfated CDs (HS-CDs) [36][37][38][39][40][41] are still the predominant CSs due to their resolution powers and commercial-availability. Since commercially available S-CDs and HS-CDs from Beckmann Coulter are not single isomers but a mixture of sulfated CDs with a different degree of substitution (average; 9 and 12, respectively), a wide range of OTG, 1-S-octyl-␤-d-thioglucopyranoside; DTDP, 3-(4,6-dichloro-1,3,5-triazinylamino)-7-dimethyamino-2-methylphenazine; LED-IF, light-emitting diode-induced fluorescence.…”

“…On the other hand, various types of cationic CDs have been synthesized and applied to the CDEKC analysis of amino acid racemates [44][45][46][47][48][49][50][51][52][53][54][55][56][57][58][59][60][61][62]. In contrast to anionic CDs, BGSs with pH 5-8,which is effective for separating neutral amino acids, are applied to EKC using cationic CDs (Table 2).…”

Advances in the enantioseparation of β‐blocker drugs by capillary electromigration techniques

“…To our knowledge, no reviews have been published so far on this specific topic, with the exception of a review article in Slovak language published in 2004 [26]. Several reviews on pharmaceutical and biomedical applications have been published in the last years describing some of the chiral CE and CEC methods developed for the enantioseparation of b-blocker drugs [27][28][29][30][31]. This review covers literature published from January 2000 to December 2010.…”