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1.
The enantioresolution of zolmitriptan was performed using cyclodextrin (CD)-modified capillary zone electrophoresis (CZE)
with hydroxypropyl-β-CD (HP-β-CD) as the chiral selector. The influence of experimental conditions on the enantioseparation
of zolmitriptan, such as pH, temperature, applied voltage, and concentrations of running electrolyte and CD, was systematically
investigated, obtaining a baseline separation of two enantiomers by the use of a 25 mM sodium dihydrogen phosphate (SDPH)
running electrolyte (pH 2.4) containing 30 mM HP-β-CD at 15 °C. Binding constants for each enantiomer–HP-β-CD pair at different
temperatures, as well as thermodynamic parameters for binding, were calculated. A nonlinear van’t Hoff plot was obtained,
indicating that the thermodynamic parameters of complexation were temperature-dependent for zolmitriptan enantiomers. The
significant contribution of the enthalpy difference to the Gibbs free energy change suggested a stereomeric barrier mechanism
for chiral recognition.
Figure Resolution of zolmitriptan enantiomers was achieved by using CD-modified CZE
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
2.
Zaher M Ravelet C Baussanne I Ravel A Grosset C Décout JL Peyrin E 《Analytical and bioanalytical chemistry》2009,393(2):655-660
In this paper, we describe the preparation and the evaluation of a porous graphitic carbon (PGC) column coated with a new
dinaphthyl derivative of neamine for chiral ligand-exchange (LE) chromatography. It was shown that the graphitic surface/dinaphthyl
anchor system efficiently (1.15 μmol/m2) and stably (three months of intensive use) adsorbs the neamine template onto the chromatographic support. The resulting
coated PGC stationary phase showed appreciable LE-based enantioselective properties towards several native amino acids.
Chromatographic separation of methionine enantiomers using a dinaphtyl neamine-based ligand-exchange chiral stationary phase 相似文献
3.
Han X Wang C He L Beesley TE Armstrong DW 《Analytical and bioanalytical chemistry》2007,387(8):2681-2697
A new synthetic polymeric chiral stationary phase for liquid chromatography was prepared via free-radical-initiated polymerization
of trans-9,10-dihydro-9,10-ethanoanthracene-(11S,12S)-11,12-dicarboxylic acid bis-4-vinylphenylamide. The new polymeric chiral stationary phase (CSP) showed enantioselectivity
for many chiral compounds in multiple mobile phases. High stability and sample capacities were observed on this polymeric
chiral stationary phase. Mobile phase components and additives affected chiral separation greatly. This new synthetic chiral
stationary phase is complementary to two other related commercially available CSPs: the P-CAP and P-CAP-DP columns. Interactions
between the chiral stationary phase and analytes that lead to retention and chiral recognition include hydrogen bonding, dipolar,
and π–π interactions. Repulsive (steric) interactions also contribute to chiral recognition.
Figure LC chromatograms showing the analytical (blue) and preparative (red) separations of N-(3,5-dinitrobenzoylleucine) enantiomers on a new synthetic polymeric chiral stationary phase 相似文献
4.
Moussa Mbaye Mame Diabou Gaye Seye Atanasse Coly Alphonse Tine Jean-Jacques Aaron 《Analytical and bioanalytical chemistry》2009,394(4):1089-1098
The photochemically induced fluorescence (PIF) spectral properties of α-cypermethrin in organic solvents (hexane, dichloromethane,
acetonitrile, ethanol) and in cyclodextrin aqueous solutions (β-CD and 2-hydroxypropyl-β-CD, 2-HP-β-CD) were investigated.
The photolysis kinetics of α-cypermethrin were evaluated in the various media. The PIF signal was found to be significantly
enhanced in the CD media relative to the organic solvents. The stoichiometry and the formation constants of the α-cypermethrin
inclusion complexes formed with the CDs were determined. The analytical performances of the PIF method were improved in the
presence of HP-β-CD relative to the other media, and a CD-enhanced PIF analytical method was developed. The limits of detection
and limits of quantification ranged, respectively, between 6 and 98 ng/mL and between 24 and 343 ng/mL, depending on the medium.
Application to the analysis of tap water and Senegal natural water samples collected close to agricultural areas and spiked
with α-cypermethrin yielded satisfactory recoveries going from about 77% to 98%. An interference study of foreign species,
including pesticides and inorganic ions likely to be present in natural waters, was also carried out.
Figure Photolysis reaction of α-cypermethrin in presence of HP-β-CD 相似文献
5.
Raghunath B. Toche Bhausaheb K. Ghotekar Muddassar A. Kazi Madhukar N. Jachak 《Monatshefte für Chemie / Chemical Monthly》2009,140(2):235-241
Abstract A novel method for the synthesis of 3-(2-substituted ethyl)-2-methylbenzohetero[3,2-a]pyrimidines in high yield (80–85%) was achieved, which involves a dihydrofuranone intermediate, readily obtained from β-ketolactone
to 2-aminobenzoheterocycles. The major advantage of the methodology is the high yield and product purity.
Graphical Abstract
相似文献
6.
Preparative HPLC separation of bambuterol enantiomers and stereoselective inhibition of human cholinesterases 总被引:2,自引:0,他引:2
Gazić I Bosak A Sinko G Vinković V Kovarik Z 《Analytical and bioanalytical chemistry》2006,385(8):1513-1519
We separated and characterized the enantiomers of bambuterol (5-[-(tert-butylamino)-1-hydroxyethyl]-m-phenylene-bis(dimethylcarbamate) hydrochloride), which is used in racemic form as a prodrug of terbutaline, a β2-adrenoceptor agonist. The enantioseparation was attempted on several chiral HPLC columns, and the most effective separation
was achieved on the amylose-based Chiralpak AD column. Since in vivo conversion of bambuterol into terbutaline involves hydrolysis
by butyrylcholinesterase (EC 3.1.1.8), we studied the reaction of enantiomers with eight human BChE variants. Both enantiomers
inhibited all studied BChE variants; however, the rate of inhibition with the (R)-enantiomer was about five times faster than with the (S)-enantiomer. (R)-bambuterol inhibition rate constants for homozygous usual (UU), fluoride-resistant (FF) or atypical (AA) variant ranged
from 6.4 to 0.11 min-1μM-1. The inhibition rates for heterozygotes were between the respective constants for the corresponding homozygotes.
An erratum to this article can be found at 相似文献
7.
Magdalena C. Waldhier Michael A. Gruber Katja Dettmer Peter J. Oefner 《Analytical and bioanalytical chemistry》2009,394(3):695-706
Free amino acids are typically quantified as the sum of their enantiomers, because in terrestrial organisms they mainly exist
in the left-handed form. However, with increasing understanding of the biological significance of right-handed amino acids
interest in enantioselective quantification of amino acids has steadily increased. Initially, electrophoretic and chromatographic
methods using chiral (pseudo)-stationary phases or chiral eluents were applied to the separation of amino acid enantiomers.
Later, derivatization of amino acids prior to chromatography with chiral reagents gained in popularity, because the diastereomers
formed can be resolved on conventional reversed-phase columns. Novel multi-interaction chiral columns turned attention back
to direct chiral chromatographic methods. Hyphenation to mass spectrometry has increasingly replaced optical detection because
of superior selectivity, although this has not obviated the need for baseline resolution of amino acid enantiomers. Despite
the progress made, enantioselective separation and quantification of amino acids remains an analytical challenge owing to
frequently incomplete resolution of all naturally occurring enantiomers and insufficient sensitivity for the determination
of the trace amounts of d-amino acids typically found in biological fluids and tissues.
Chiral GC-MS analysis of heptafluorobutanol/pentafluoropropionanhydride amino acid derivatives on an Rt-gDEXsa column 相似文献
8.
András Gergely Péter Horváth György Szász Gábor Veress 《Analytical and bioanalytical chemistry》2009,394(8):2105-2109
A three-step gradient reversed-phase high-performance liquid chromatography (RP-HPLC) method was developed for the separation
of dehydroepiandrosterone (DHEA), its sulfate ester (DHEA-S), its three C7-oxidized metabolites (7αOH-DHEA, 7βOH-DHEA, 7-keto-DHEA),
and its biosynthetic congeners (androstenedione, testosterone, estradiol, pregnenolone). This new method allows the quantitative
characterization of DHEA metabolism and biosynthetic transformation under given physiological, pathological, or therapeutically
influenced circumstances. Tetrahydrofuran probably acts as a proton acceptor coadsorbent, while isopropanol behaves as a proton
donor during the separation of testosterone, estradiol, and the stereoisomers of 7-OH-DHEA.
Figure Optimized gradient RP-HPLC results in full separation of DHEA from its biosynthetic congeners and metabolites 相似文献
9.
Christian V. Hoffmann Michael Lämmerhofer Wolfgang Lindner 《Analytical and bioanalytical chemistry》2009,393(4):1257-1265
A recently reported chiral strong cation exchanger (cSCX) type stationary phase was investigated for the LC separation of
a series of Cinchona alkaloids and synthetic derivatives thereof to test its usefulness as alternative methodology for the separation of those
important pharmaceuticals. The cSCX column-packing material was qualitatively compared on the one hand against a commercially
available non-enantioselective SCX-material, PolySulfoethyl-A, and, on the other hand, against a modern C18 reversed-phase
stationary phase which is commonly employed for Cinchona alkaloid analysis. Both SCX columns showed no pronounced peak-tailing phenomena which typically hamper Cinchona alkaloid RP analysis and require specific optimization. Thus, the cSCX-based assay provided new feasibilities for the separation
of the Cinchona alkaloids in polar organic mode as opposed to conventional reversed-phase methodologies. In particular, a method for the
simultaneous determination of eight Cinchona alkaloids (quinine, quinidine, cinchonine, cinchonidine, and their corresponding dihydro analogs) using the cSCX column in
HPLC has been developed and exemplarily applied to impurity profiling of a commercial alkaloid sample. Furthermore, both SCX
materials allowed successful separation of C9-epi and 10,11-didehydro derivatives from their respective educts in an application
in synthetic Cinchona alkaloid chemistry.
Figure An alternative separation principle - HPLC separation of strongly basic natural Cinchona alkaloids and synthetic derivatives thereof by means of a strong cation-exchanger type chiral stationary phase 相似文献
10.
Ion mobility spectrometry is an analytical method for identification and quantification of gas-phase analytes in the ppbv-pptv range. Traditional ionisation methods suffer from low sensitivity (UV light), lack of long-term stability (partial discharge),
or legal restrictions when radioactive sources are used. A miniaturised helium plasma was applied as ionisation source in
an ion mobility spectrometer (IMS). Experiments were carried out to compare plasma IMS with β-radiation IMS. It could be demonstrated
that the plasma IMS is characterised by higher sensitivity and selectivity than β-radiation ionisation. Plasma IMS is approximately
100 times more sensitive than the β-radiation IMS. Furthermore, variable sensitivity can be achieved by variation of the helium
flow and the electric field of the plasma, and variable selectivity can be achieved by changing the electric field of the
IMS. The experimental arrangement, optimisation of relevant conditions, and a typical application are presented in detail.
Figure Micro-plasma used in ion mobility spectrometry 相似文献
11.
Zhi-zhong Wang Wei Jiao Guang-yun He Run-hua Lu 《Monatshefte für Chemie / Chemical Monthly》2009,140(1):79-81
Abstract A simple method for the straightforward regioselective synthesis of 2,3-mannoepoxy-β-cyclodextrin, which is a valuable precursor for further functionalization of β-cyclodextrin, is achieved under aqueous conditions without any organic solvents at a moderate yield.
Graphical abstract
相似文献
12.
Kahina Si-Ahmed Fairouz Tazerouti Ahmed Y. Badjah-Hadj-Ahmed 《Analytical and bioanalytical chemistry》2009,395(2):507-518
In order to study the effect of the nature and the length of the spacer, three mixed 10-undecenoate/phenylcarbamate derivatives
of β-cyclodextrin have been prepared and linked to allylsilica gel by means of a radical reaction. The chiral recognition
ability of the resulting materials, when used as liquid chromatography chiral stationary phases (CSPs), was evaluated using
heptane and either 2-propanol or chloroform as organic mobile-phase modifiers. A large variety of racemic compounds have been
separated successfully on these CSPs (mainly pharmaceuticals and herbicides). Optimization of these separations was discussed
in terms of mobile-phase composition and structural patterns of the injected analytes. The efficiencies of the three prepared
materials were compared to those of previously described perphenylated-β-cyclodextrin column and to analogous cellulose derivative-based
CSPs.
Schematic illustration of the b-cyclodextrin/mandelic acid inclusion complex 相似文献
13.
Do-Min Lee Gullapalli Kumaraswamy Kee-In Lee 《Monatshefte für Chemie / Chemical Monthly》2009,140(1):73-78
Abstract Catalytic transfer hydrogenation of α-tosyloxyarylketones mediated by a chiral rhodium complex using an azeotropic mixture
of formic acid/triethylamine afforded the corresponding 1-arylethanediol monotosylates in excellent yield with high enantioselectivity.
Graphical abstract
相似文献
14.
Jolanta Pawłowska Krzysztof K. Krawczyk Krystyna Wojtasiewicz Jan K. Maurin Zbigniew Czarnocki 《Monatshefte für Chemie / Chemical Monthly》2009,140(1):83-86
Abstract (+)-Lortalamine was synthesised using (S)-(−)-α-methylbenzylamine as a chiral auxiliary. The stereochemistry of an intermediate compound was established on the basis
of X-ray crystallography, allowing unambiguous assignment of the absolute configuration.
Graphical abstract
相似文献
15.
Eric B. Kalman Olivier Sudre Ivan Vlassiouk Zuzanna S. Siwy 《Analytical and bioanalytical chemistry》2009,394(2):413-419
Control of ionic transport through nanoporous systems is a topic of scientific interest for the ability to create new devices
that are applicable for ions and molecules in water solutions. We show the preparation of an ionic transistor based on single
conical nanopores in polymer films with an insulated gold thin film “gate.” By changing the electric potential applied to
the “gate,” the current through the device can be changed from the rectifying behavior of a typical conical nanopore to the
almost linear behavior seen in cylindrical nanopores. The mechanism for this change in transport behavior is thought to be
the enhancement of concentration polarization induced by the gate.
Figure
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
16.
Bohumil Proksa Richard Hercek Tibor Liptaj Nada Prónayová 《Monatshefte für Chemie / Chemical Monthly》2009,140(5):485-487
Abstract A new compound was isolated from the reaction mixture after O-demethylation of 6-O-acetyl-10α-acetoxycodeine with boron tribromide. The structure of this compound, 10α-hydroxy-β-isomorphine, was elucidated by spectral data, and its spatial arrangement was deduced from an NOE experiment. Capillary zone
electrophoresis was used for separation of morphine and its 10-hydroxy analogues.
Graphical abstract
相似文献
17.
The use of polymers in microchip fabrication affords new opportunities for the development of powerful, miniaturized separation
techniques. One method in particular, the use of phase-changing sacrificial layers, allows for simplified designs and many
additional features to the now standard fabrication of microchips. With the possibility of adding a third dimension to the
design of separation devices, various means of enhancing analysis now become possible. The application of phase-changing sacrificial
layers in microchip analysis systems is discussed, both in terms of current uses and future possibilities.
Figure Phase-changing sacrificial materials enable multilayer microfluidic device layouts 相似文献
18.
In-torch LA–ICP–MS was implemented into an in-house-built ICP–TOFMS system. The fast data acquisition capabilities of the
new configuration allowed simultaneous multi-element measurement and readout of in-torch LA–ICP–MS signals with 30 μs time
resolution. The measurements confirmed previously observed fine structures of in-torch generated signals and provided new
insights in the dynamic processes in the plasma on a microsecond time scale. The new setup is described in detail and first
figures of merit are given.
Figure Time dependent multi element signal after laser ablation in the torch of an ICP-TOFMS instrument 相似文献
19.
Abstract The title compound, labeled with 13C in the ethyl groups was synthesized from K13CN and low-molecular-weight components. The synthetic relay compound was 31(32)[13C]-xanthobilirubinic acid methyl ester in a synthetic route that leads to a label in the ethyl β-substituent of a dipyrrinone
model for bilirubin. This labeled dipyrrinone was oxidatively coupled to the dimethyl ester of mesobiliverdin-XIIIα, thereby
providing a route to a 13C-labeled mesobiliverdin and mesobilirubin, with one carbon of each ethyl being 98% 13C-enriched.
Graphical Abstract
相似文献
20.
Tse Sum Bui B Belmont AS Witters H Haupt K 《Analytical and bioanalytical chemistry》2008,390(8):2081-2088
A β-estradiol receptor binding mimic was synthesised using molecular imprinting. Bulk polymers and spherical polymer nanoparticles
based on methacrylic acid and ethylene glycol dimethacrylate as the functional monomer and crosslinker, respectively, were
prepared in acetonitrile. The selectivity was evaluated by radioligand binding assays. The imprinted polymers were very specific
to β-estradiol since the control polymers bound virtually none of the radioligand. The bulk polymer was then employed to screen
endocrine disrupting chemicals. Structurally related steroids like α-estradiol, estrone and ethynylestradiol showed, respectively,
14.0, 5.0 and 0.7% of relative binding to the β-estradiol polymer, whereas most unrelated chemicals did not bind at all. These
results are compared to those obtained with a bioassay using stably transfected yeast cells in culture bearing the human estrogen
receptor. The receptor was activated by several estrogen-like chemicals and to a lesser extent by some structurally related
chemicals.
Figure A molecularly imprinted polymer that was a synthetic receptor for beta-estradiol was used for the screening of endocrine disrupting
chemicals that are structurally related or unrelated to beta-estradiol. The results were compared with the recognition of
the compounds by the biological estrogen receptor expressed in yeast cells. Related steroids like alpha-estradiol, estrone
and ethynylestradiol showed significant binding to the beta-estradiol imprinted polymer, whereas most unrelated chemicals
did not bind. The biological receptor was activated by several estrogen-like chemicals, and to a lesser extent by some structurally
related chemicals 相似文献