Selectivity in capillary electrokinetic separations

Boer, Theo de; Zeeuw, Rokus A. de; Jong, Gerhardus J. de; Ensing, K

doi:10.1002/(sici)1522-2683(19991001)20:15/16<2989::aid-elps2989>3.0.co;2-x

Cited by 36 publications

(41 citation statements)

References 150 publications

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“…Without good n, number of determinations selectivity, it is cumbersome to achieve accuracy, precision, and linearity [30,38]. The drugs mebendazole, dexamethasone, phenytoin, valproic acid, primidone, phenobarbital, and carbamazepine are often administered in combination with ABZ and were evaluated as possible interferents.…”

Section: Methods Validationmentioning

confidence: 99%

Enantioselective analysis of albendazole sulfoxide in cerebrospinal fluid by capillary electrophoresis

Paias

Lanchote²,

Takayanagui

et al. 2001

Electrophoresis

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Albendazole (ABZ) is a benzimidazole anthelmintic drug used in the treatment of neurocysticercosis. After oral administration, ABZ is rapidly oxidized to albendazole sulfoxide (ABZSO), which has an asymmetric sulfur center, and later to albendazole sulfone (ABZSO2). ABZSO is the active metabolite responsible for the therapeutic effect of the drug. Previous studies have demonstrated pharmacokinetic differences between the two enantiomers, with the predominance of (+)-ABZSO in human biological fluids. This article describes for the first time the enantioselective analysis of ABZSO in cerebrospinal fluid (CSF) using capillary electrophoresis. The samples were prepared by liquid-liquid extraction using chloroform:isopropanol (8:2 v/v). The resolution of ABZSO enantiomers was obtained with a fused-silica capillary (60 cm x 75 microm ID) using 20 mmol/L Tris, pH 7.0, with 3.0% w/w sulfated beta-cyclodextrin as running buffer. The coefficient of variations and % relative error obtained for both within-day and between-days assays were lower than 15%. The method was linear over the concentration range of 100 to 2,500 ng/mL for each enantiomer, indicating that it is suitable for the analysis of ABZSO enantiomers in CSF from patients medicated with ABZ.

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Section: Methods Validationmentioning

confidence: 99%

Enantioselective analysis of albendazole sulfoxide in cerebrospinal fluid by capillary electrophoresis

Paias

Lanchote²,

Takayanagui

et al. 2001

Electrophoresis

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“…The use of CE for chiral separations has three major advantages in comparison with HPLC: the low consumption of the chiral selector (reduced costs), high efficiencies, and high selectivity [5]. Besides the oftenused neutral CDs, the use of charged CD derivatives has expanded the range of applicability of this technique for chiral analysis [6].…”

Section: Introductionmentioning

confidence: 99%

Comparison of charged cyclodextrin derivatives for the chiral separation of atropisomeric polychlorinated biphenyls by capillary electrophoresis

2003

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Comparison of charged cyclodextrin derivatives for the chiral separation of atropisomeric polychlorinated biphenyls by capillary electrophoresisCharged cyclodextrin (CD) derivatives were used as chiral selectors in electrokinetic chromatography (EKC) for the chiral separation of highly hydrophobic neutral racemates such as atropisomeric polychlorinated biphenyls (PCBs). b-CD-phosphated, b-CD sulfated, succinylated-g-CD (Succ-g-CD) and succinylated-b-CD (Succ-b-CD) were used as anionic CDs. As cationic CD, 6-monodeoxy-6-monoamino-b-CD (b-CD-NH 2 ) was tested for the first time in order to separate PCBs. From the different CD derivatives employed, the best separations were obtained with the cationic CD derivative. Thus, the use of b-CD-NH 2 in phosphate buffer at pH 2.0 containing urea allowed the chiral recognition of eleven PCBs (45, 84, 88, 91, 95, 131, 136, 144, 149, 176, and 197). In this case, the addition of 2 M urea to the buffer solution was crucial to achieve the chiral separation of PCBs. The addition of acetonitrile to 10 mM phosphate buffer (pH 2.0) with 30 mM b-CD-NH 2 and 2 M urea improved considerably the chiral resolution obtained for PCBs 91, 95, 136, 144, 149, and 197 although an increase in the analysis time was also observed. All the results obtained were compared with those previously obtained with the dual CD system carboxymethyl-g-CD/b-CD.

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“…(ii) Already at concentrations below the CMC, they interact selectively with sample analytes and BGE components, which, together with related changes in the EOF, are used to optimize the selective separation of analytes [7][8][9][10][11][12][13][14]. (iii) They change properties of the BGE such as the viscosity of the BGE solution, and they often create a pseudostationary phase, by using concentrations above the CMC and this is applied in micellar electrokinetic capillary chromatography (MEKC) ( [15, 16, for recent reviews see [17][18][19]). Obviously, the presence of a surfactant as an additive to a BGE always brings a complex situation where several effects are superimposed and mutually influenced.…”

Section: Introductionmentioning

confidence: 99%

Multiple effect of surfactants used as additives in background electrolytes in capillary zone electrophoresis: Cetyltrimethylammonium bromide as example of model surfactant

Beckers

Boček

2002

Electrophoresis

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Surfactants are frequently used in the preparation of background electrolytes (BGEs) in capillary zone elcetrophoresis (CZE) in order to affect and to optimize both the electroosmotic flow (EOF) and the separation process. Their effects are, however, always multiple, the resulting situation may be very complex and the separation process may even be destroyed. We use the surfactant cetyltrimethylammonium bromide (CTAB) as a model example and bring experimental results and related discussion which elucidate the multiple effect of surfactants in an integrated way. It is shown that even at concentration levels lower than 10(-4) M CTAB strongly reduces the cathodic EOF in bare fused-silica capillaries and converts it into anodic EOF. The magnitude and polarity of the EOF depends not only on the concentration of CTAB but also on the composition of BGEs used. The interactions of CTA cations with the bare capillary wall reduce sorption of cationic analytes and enables their analysis. CTA cations at levels below their critical micelles concentration (CMC) already interact with anionic analytes and reduce their mobilities. This association is strong with highly charged anions and by this, the reversal of the EOF, applying BGEs with highly charged anions is less effective. These interactions are competitive and also depend on the composition of the BGE used. At levels above its CMC, CTAB forms micelles and enables the application of the micellar electrokinetic capillary chromatography (MEKC) mode and the analysis of, e.g., neutral components. Simultaneously, it is shown that the presence of CTAB may increase the number of potentially formed system zones.

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Selectivity in capillary electrokinetic separations

Cited by 36 publications

References 150 publications

Enantioselective analysis of albendazole sulfoxide in cerebrospinal fluid by capillary electrophoresis

Enantioselective analysis of albendazole sulfoxide in cerebrospinal fluid by capillary electrophoresis

Comparison of charged cyclodextrin derivatives for the chiral separation of atropisomeric polychlorinated biphenyls by capillary electrophoresis

Multiple effect of surfactants used as additives in background electrolytes in capillary zone electrophoresis: Cetyltrimethylammonium bromide as example of model surfactant

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