| 1. |
- Hedeland, Ylva, et al.
(author)
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Chiral separation of amines with N-benzoxycarbonylglycyl-L-proline as selector in non-aqueous capillary electrophoresis using methanol and 1,2-dichloroethane in the background electrolyte
- 2003
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In: Journal of Chromatography A. - 0021-9673 .- 1873-3778. ; 984:2, s. 261-271
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Journal article (peer-reviewed)abstract
- N-Benzoxycarbonylglycyl-L-proline (L-ZGP) has been introduced as a chiral selector for enantioseparation of amines in non-aqueous capillary electrophoresis. Methanol mixed with different proportions of dichloromethane, 1,2-dichloroethane or 2-propanol containing L-ZGP and ammonium acetate was used as the background electrolyte. Enantioseparation of different types of pharmacologically active amines was performed, e.g. the local anaesthetic bupivacaine and the beta-adrenoceptor blocking agent pindolol. Addition of the solvents (dichloromethane, 1,2-dichloroethane or 2-propanol) gave an improved chiral separation partly due to a distinct decrease in the electroosmotic flow. The use of 1,2-dichloroethane in the background electrolyte gave higher precision in migration time (RSD 2.2%) compared to the systems containing dichloromethane. An enantiomeric separation of mepivacaine was performed within 72 s by use of short-end injection with an effective capillary length of 8.5 cm.
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| 2. |
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| 3. |
- Lodén, Henrik, et al.
(author)
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Development of a chiral non-aqueous capillary electrophoretic system using the partial filling technique with UV and mass spectrometric detection
- 2003
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In: Journal of Chromatography A. - : Elsevier. - 0021-9673 .- 1873-3778. ; 986:1, s. 143-152
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Journal article (peer-reviewed)abstract
- A chiral non-aqueous CE system with UV and mass spectrometric detection has been developed. The enantioseparation was promoted by diastereomeric complex (ion-pair) formation between the amines (e.g. salbutamol, atenolol) and the chiral selector, (-)-2,3:4,6-di-O-isopropylidene-2-keto-L-gulonic acid [(-)-DIKGA]. Different solvent mixtures were studied, as well as different concentrations of (-)-DIKGA and ammonium acetate in the background electrolyte. A partial filling technique was developed with a selector plug composed of (-)-DIKGA and ammonium acetate in a solvent mixture of methanol and 2-propanol. The separated enantiomers of pronethalol were detected by a Q-TOF MS system equipped with a sheath-flow electrospray ionization interface.
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| 4. |
- Carlsson, Ylva, et al.
(author)
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Non-aquoeus capillary electrophoretic separation of enantiomeric amines with (-)-2,3:4,6-di-O-isopropylidene-2-keto-L-gulonic acid as chiral counter ion
- 2001
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In: Journal of Chromatography A. - : Elsevier. - 0021-9673. ; 922:1-2, s. 303-311
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Journal article (peer-reviewed)abstract
- (2)-2,3:4,6-Di-O-isopropylidene-2-keto-L-gulonic acid [(2)-DIKGA] has been introduced as a chiral counter ion innon-aqueous capillary electrophoresis. High enantioresolutions (R $3) were obtained for amines, e.g., pronethalol, labetalol Sand bambuterol. Methanol containing NaOH and (2)-DIKGA was used as the background electrolyte. The counter ionconcentration and the nature of the injection medium were found to affect the chiral separation. Covalent coating of thefused-silica capillary reduced the electro-osmotic flow resulting in improved enantioresolutions.
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| 5. |
- Hedeland, Mikael, et al.
(author)
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Simultaneous quantification of the enantiomers of verapamil and its N-demethylated metabolite in human plasma using liquid chromatography-tandem mass spectrometry
- 2004
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In: Journal of chromatography. B. - : Elsevier BV. - 1570-0232 .- 1873-376X. ; 804:2, s. 303-311
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Journal article (peer-reviewed)abstract
- A stereoselective bioanalytical method for the simultaneous quantification of the enantiomers of verapamil and its active main metabolite norverapamil in human plasma has been developed and validated. The samples were analysed by liquid chromatography-electrospray-tandem mass spectrometry (LC-ESI-MS/MS) in the Selected Reaction Monitoring (SRM) mode using a deuterated internal standard. The stationary phase used for the chiral separation was a Chiral-AGP. The enantiomers of verapamil were selectively detected from those of norverapamil by the mass spectrometer due to different molecular masses, although there was a chromatographic co-elution. Thus, time-consuming procedures like achiral preseparation or chemical derivatisation could be avoided. Higher detection sensitivity than earlier published methods based on fluorescence detection was obtained, although a mobile phase of high water-content and high flow-rate was introduced into the electrospray interface (85% aqueous ammonium acetate pH 7.4 +15% acetonitrile at 0.6 ml/min). The enantiomers of verapamil and norverapamil could be quantified at levels down to 50 pg and 60 pg/500 microl plasma sample, respectively, with R.S.D. in the range of 3.6-7.8%. The presented method was successfully applied to an in vivo intestinal absorption and bioavailability study in humans, using the Loc-I-Gut method.
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