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Chiral separation

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https://www.readbyqxmd.com/read/28340473/enantiomers-of-triclabendazole-sulfoxide-analytical-and-semipreparative-hplc-separation-absolute-configuration-assignment-and-transformation-into-sodium-salt
#1
Rosella Ferretti, Simone Carradori, Paolo Guglielmi, Marco Pierini, Adriano Casulli, Roberto Cirilli
Direct HPLC separation of the enantiomers of triclabendazole sulfoxide (TCBZ-SO), which is the main metabolite of the anthelmintic drug triclabendazole, was carried out using the polysaccharide-based Chiralpak AS-H and Chiralpak IF-3 chiral stationary phases (CSPs). The chromatographic behaviour of both CSPs was evaluated and compared using normal-phase and reversed-phase eluents at different column temperatures. The eluent mixture of n-hexane-2-propanol-trifluoroacetic acid 70:30:0.1 (v/v/v) and a column temperature of 40°C were identified as the best operational conditions to carry out semipreparative enantioseparations on a 1-cm I...
March 16, 2017: Journal of Pharmaceutical and Biomedical Analysis
https://www.readbyqxmd.com/read/28335970/quinine-bonded-to-superficially-porous-particles-for-high-efficiency-and-ultrafast-liquid-and-supercritical-fluid-chromatography
#2
Darshan C Patel, Zachary S Breitbach, JeongJae Yu, Kate A Nguyen, Daniel W Armstrong
Two new anion-exchange columns were prepared by bonding tert-butyl carbamoylated quinine to 2.7 μm superficially porous particle (SPP) silica to create chiral stationary phases for high-efficiency and ultrafast chromatography. Performance and retention parameters of these new columns are compared with an analogous 5 μm fully porous particle (FPP) based Chiralpak QNAX column and a 3-4 fold increase in efficiency was observed. Ultrafast separations ranging from 12 s down to sub-second are shown using 2.7 μm SPPs bonded via hydrosilation to the selector...
April 22, 2017: Analytica Chimica Acta
https://www.readbyqxmd.com/read/28335532/separation-of-alkyne-enantiomers-by-chiral-column-hplc-analysis-of-their-cobalt-complexes
#3
Qiaoyun Liu, Jing Wang, Junfei Li, Xiaolei Wang, Shichao Lu, Xuan Li, Yaling Gong, Shu Xu
Separation of the enantiomers of new chiral alkynes in strategic syntheses and bioorthogonal studies is always problematic. The chiral column high-performance liquid chromatography (HPLC) method in general could not be directly used to resolve such substrates, since the differentiation of the alkyne segment with the other alkane/alkene segment is not significant in the stationary phase, and the alkyne group is not a good UV chromophore. Usually, a pre-column derivatization reaction with a tedious workup procedure is needed...
March 20, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/28328068/separation-of-enilconazole-enantiomers-in-capillary-electrophoresis-with-cyclodextrin-type-chiral-selectors-and-investigation-of-structure-of-selector-selectand-complexes-by-using-nuclear-magnetic-resonance-spectroscopy
#4
Ann Gogolashvili, Elene Tatunashvili, Lali Chankvetadze, Tamas Sohajda, Julianna Szeman, Antonio Salgado, Bezhan Chankvetadze
In the present study the enantiomer migration order (EMO) of enilconazole in the presence of various cyclodextrins (CDs) was investigated by capillary electrophoresis (CE). Opposite EMO of enilconazole were observed when β-CD or the sulfated heptakis(2-O-methyl-3,6-di-O-sulfo)-β-CD (HMDS-β-CD) was used as the chiral selectors. Nuclear Magnetic Resonance (NMR) spectroscopy was used to study the mechanism of chiral recognition between enilconazole enantiomers and those two cyclodextrins. On the basis of rotating frame nuclear Overhauser (ROESY) experiments, the structure of an inclusion complex between enilconazole and β-CD was derived, in which (+)-enilconazole seemed to form a tighter complex than the (-)-enantiomer...
March 22, 2017: Electrophoresis
https://www.readbyqxmd.com/read/28322560/subphthalocyanines-axially-substituted-with-a-tetracyanobuta-1-3-diene-aniline-moiety-synthesis-structure-and-physicochemical-properties
#5
Kim A Winterfeld, Giulia Lavarda, Julia Guilleme, Michael Sekita, Dirk M Guldi, Tomas Torres, Giovanni Bottari
A 1,1,4,4-tetracyanobuta-1,3-diene (TCBD)-aniline moiety has been introduced, for the first time, at the axial position of two subphthalocyanines (SubPcs) peripherally substituted with hydrogen (H12SubPc) or fluorine atoms (F12SubPc). Single-crystal X-ray analysis of both SubPc-TCBD-aniline systems showed that each conjugate is a racemic mixture of two atropisomers resulting from the almost orthogonal geometry adopted by the axial TCBD unit, which were separated by chiral HPLC. Remarkably, the single-crystal X-ray structure of one atropisomer of each SubPc-TCBD-aniline conjugate has been solved allowing to unambiguously assign the atropisomers' absolute configuration, something, to the best of our knowledge, unprecedented in TCBD-based conjugates...
March 21, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28319864/enantioselective-degradation-of-alpha-cypermethrin-and-detection-of-its-metabolites-in-bullfrog-rana-catesbeiana
#6
Guojun Yao, Xu Jing, Chang Liu, Peng Wang, Xueke Liu, Yinzhu Hou, ZhiQiang Zhou, Donghui Liu
Bullfrog, as a kind of amphibians, can be easily exposed to varied pollutants in the environment for the reason of its habitats and highly permeable skin. We investigated the degradation kinetics and residues of α-cypermethrin in bullfrog by two different methods of administration for the environmental monitoring the behavior of one of the most used pesticides in the amphibians. The oral administration and water exposure of α-cypermethrin on bullfrog was studied in this work. α-Cypermethrin and its main metabolites of cis-3-(2',2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid (cis-DCCA) and 3-phenoxybenzoic acid (3-PBA), which have been determined that having correlation with a number of epidemic diseases, were detected simultaneously...
March 17, 2017: Ecotoxicology and Environmental Safety
https://www.readbyqxmd.com/read/28318564/comparing-the-selectivity-and-chiral-separation-of-d-and-l-fluorenylmethyloxycarbonyl-chloride-fmoc-protected-amino-acids-in-analytical-high-performance-liquid-chromatography-and-supercritical-fluid-chromatography-evaluating-throughput-economic-and-environmental
#7
C M Vera, D Shock, G R Dennis, W Farrell, R A Shalliker
The chiral separation of d- and l- FMOC amino acids was undertaken using the Lux Cellulose-1 polysaccharide based chiral column in HPLC (normal phase and reverse phase) and SFC conditions. This was done to compare the relative selectivity and separation between the three separation modes and to evaluate the potential benefits of SFC separations with regards to resolution, throughput, economic and environmental impact. It was established that the separation of d- and l- FMOC amino acids in SFC displayed behaviours that were similar to both normal phase and reversed phase, rather than distinctly one or the other...
February 16, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28317942/wide-dynamic-range-enrichment-method-of-semiconducting-single-walled-carbon-nanotubes-with-weak-field-centrifugation
#8
Wieland G Reis, Željko Tomović, R Thomas Weitz, Ralph Krupke, Jules Mikhael
The potential of single-walled carbon nanotubes (SWCNTs) to outperform silicon in electronic application was finally enabled through selective separation of semiconducting nanotubes from the as-synthesized statistical mix with polymeric dispersants. Such separation methods provide typically high semiconducting purity samples with narrow diameter distribution, i.e. almost single chiralities. But for a wide range of applications high purity mixtures of small and large diameters are sufficient or even required...
March 20, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28288350/effects-of-wastewater-irrigation-and-sewage-sludge-application-on-soil-residues-of-chiral-fungicide-benalaxyl
#9
Xu Jing, Guojun Yao, Donghui Liu, Yiran Liang, Mai Luo, Zhiqiang Zhou, Peng Wang
The effects of wastewater irrigation and sewage sludge on the dissipation behavior of the fungicide benalaxyl and its primary metabolite benalaxyl acid in soil were studied on an enantiomeric level during a 148-day exposure experiment. Chiral separation and analysis of the two pairs of enantiomers were achieved using HPLC-MS/MS with a chiralpak IC chiral column. Benalaxyl decreased with half-life of 16.1 days in soil under tap water irrigation with preferential residue of S-benalaxyl. Benalaxyl acid was formed with great preference of R-enantiomer before 21 days while enriched in S-enantiomer afterwards...
March 10, 2017: Environmental Pollution
https://www.readbyqxmd.com/read/28286575/chiral-determination-of-3-4-methylenedioxypyrovalerone-enantiomers-in-rat-serum
#10
Michael D Hambuchen, Howard P Hendrickson, S Michael Owens
The emerging stimulant drug of abuse (3,4)-methylenedioxypyrovalerone [(R,S)-MDPV] is self-administered as a racemic mixture by intranasal, iv, oral, and smoking routes. The individual enantiomers are known to have widely different pharmacological effects, with (S)-MDPV showing much greater potency than (R)-MDPV in pharmacological testing. The goal of these studies was to develop and validate an analytical method for quantitation of (R)-MDPV, (S)-MDPV and (R,S)-MDPV in small volumes of rat serum using a chiral separation column and liquid chromatography-mass spectrometry...
January 28, 2017: Analytical Methods: Advancing Methods and Applications
https://www.readbyqxmd.com/read/28279932/enantioselective-recognition-of-radezolid-by-cyclodextrin-modified-capillary-electrokinetic-chromatography-and-electronic-circular-dichroism
#11
Katarzyna Michalska, Ewa Gruba, Wojciech Bocian, Judyta Cielecka-Piontek
A method for the enantioseparation of radezolid (RAD), an analogue of a truly new class of antibacterial agents, oxazolidinones, was developed based on capillary electrokinetic chromatography using a cyclodextrin as a chiral pseudophase (CD-cEKC). The mechanism of RAD separation, together with its precursor, were investigated to directly define the relationship between the oxazolidinone structure and the complexation process. During the development of the method, anionic single isomer cyclodextrins were tested...
February 21, 2017: Journal of Pharmaceutical and Biomedical Analysis
https://www.readbyqxmd.com/read/28279931/quantitative-chiral-and-achiral-determination-of-ketamine-and-its-metabolites-by-lc-ms-ms-in-human-serum-urine-and-fecal-samples
#12
Mahmoud Hasan, Robert Hofstetter, Georg M Fassauer, Andreas Link, Werner Siegmund, Stefan Oswald
Ketamine (KET) is a widely used anesthetic drug which is metabolized by CYP450 enzymes to norketamine (n-KET), dehydronorketamine (DHNK), hydroxynorketamine (HNK) and hydroxyketamine (HK). Ketamine is a chiral compound and S-ketamine is known to be the more potent enantiomer. Here, we present the development and validation of three LC-MS/MS assays; the first for the quantification of racemic KET, n-KET and DHNK in human serum, urine and feces; the second for the separation and quantification of the S- and R-enantiomers of KET, n-KET and DHNK, and the third for separation and quantification of 2S,6S-hydroxynorketamine (2S,6S-HNK) and 2R,6R-hydroxynorketamine (2R,6R-HNK) in serum and urine with the ability to separate and detect 10 additional hydroxylated norketamine metabolites of racemic ketamine...
February 27, 2017: Journal of Pharmaceutical and Biomedical Analysis
https://www.readbyqxmd.com/read/28274119/peptide-metal-organic-frameworks-for-enantioselective-separation-of-chiral-drugs
#13
Jose Navarro-Sánchez, Ana I Argente-García, Yolanda Moliner-Martínez, Daniel Roca-Sanjuán, Dmytro Antypov, Pilar Campíns-Falcó, Matthew J Rosseinsky, Carlos Marti-Gastaldo
We report the ability of a chiral Cu(II) 3D MOF based on the tripeptide Gly-L-His-Gly (GHG) for the enantioselective separation of metamphetamine and ephedrine. Monte Carlo simulations suggest that chiral recognition is linked to preferential binding of one of the enantiomers as result of either stronger or additional H-bonds with the framework that lead to energetically more stable diastereomeric adducts. Solid phase extraction (SPE) of a racemic mixture by using Cu(GHG) as extractive phase permits isolating more than 50% of the (+)-ephedrine enantiomer as target compound in only four minutes...
March 9, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28261717/a-thermoregulated-phase-separable-chiral-pt-nanocatalyst-for-recyclable-asymmetric-hydrogenation-of-%C3%AE-ketoesters
#14
Xiuru Xue, Yanhua Wang, Fu-She Han
The design and preparation of a chiral Pt nanocatalyst system possessing thermoregulated phase-separation property and its application in recyclable asymmetric hydrogenation of α-ketoesters are presented.
March 6, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28258982/the-sodium-salt-of-the-enantiomers-of-ricobendazole-preparation-solubility-and-chiroptical-properties
#15
Roberto Cirilli, Paolo Guglielmi, Francesca Romana Formica, Adriano Casulli, Simone Carradori
Albendazole (ABZ) is a sulfanyl-benzimidazole anthelmintic drug used worldwide in the treatment and prevention of parasitic diseases in animals and humans. Following oral administration, ABZ is rapidly oxidized into the pharmacologically active chiral sulfoxide metabolite known as ricobendazole (RBZ). As its achiral precursor, RBZ shows very low intestinal absorption due to its poor solubility in water (0.06mgmL(-1)). To the best of our knowledge, there is no known example in human medicine of a water-soluble salt form of racemic or enantiomerically pure RBZ...
February 20, 2017: Journal of Pharmaceutical and Biomedical Analysis
https://www.readbyqxmd.com/read/28257571/induction-of-chiral-recognition-with-lipid-nanodomains-produced-by-polymerization
#16
Yukihiro Okamoto, Yusuke Kishi, Keishi Suga, Hiroshi Umakoshi
We report the induction and control of chiral recognition in liposomal membranes by the photopolymerization of diacetylenic lipids (DiynePC). The specific properties of polymerized DiynePC liposomes were characterized, and then the chiral separation performance was estimated. As the polymerization proceeds, chiral recognition to ibuprofen was induced, and its efficiency increased due to the formation of rigid nanodomains and boundary edges. Furthermore, the chiral recognition and adsorbed amount could be controlled by the ratio of rigid nanodomains, varying the composition ratio of DiynePC...
March 14, 2017: Biomacromolecules
https://www.readbyqxmd.com/read/28256731/sequence-requirements-of-oligonucleotide-chiral-selectors-for-the-capillary-electrophoresis-resolution-of-low-affinity-dna-binders
#17
Luma Tohala, Farid Oukacine, Corinne Ravelet, Eric Peyrin
We recently reported that a great variety of DNA oligonucleotides (ONs) used as chiral selectors in partial-filling capillary electrophoresis (CE) exhibited interesting enantioresolution properties towards low-affinity DNA binders. Herein, the sequence prerequisites of ONs for the CE enantioseparation process were studied. First, the chiral resolution properties of a series of homopolymeric sequences (Poly-dT) of different lengths (from 5 to 60-mer) were investigated. It was shown that the size increase-dependent random coil-like conformation of Poly-dT favorably acted on the apparent selectivity and resolution...
March 3, 2017: Electrophoresis
https://www.readbyqxmd.com/read/28256056/surface-imprinted-microspheres-prepared-by-a-template-oriented-method-for-the-chiral-separation-of-amlodipine
#18
Shenzhi Lai, Xiaoli Ouyang, Changqun Cai, Wensheng Xu, Chunyan Chen, Xiaoming Chen
The surface imprinting technique has been developed to overcome the mass-transfer difficulty, but the utilization ratio of template molecules in the imprinting procedure still remains a challengeable task to be improved. In this work, specifically designed surface-imprinted microspheres were prepared by a template-oriented method for enantioseparation of amlodipine besylate. Submicron mesoporous silica microspheres were surface-modified with double bonds, followed by polymerizing methacrylic acid to generate carboxyl modified mesoporous silica microspheres (PMAA@SiO2 )...
March 3, 2017: Journal of Separation Science
https://www.readbyqxmd.com/read/28252144/chiral-segregation-driven-by-a-dynamical-response-of-the-adsorption-footprint-to-the-local-adsorption-environment-bitartrate-on-cu-110
#19
G R Darling, M Forster, C Lin, N Liu, R Raval, A Hodgson
Local or global ordering of chiral molecules at a surface is a key step in both chiral separation and heterogeneous enantioselective catalysis. Using density functional theory and scanning probe microscopy results, we find that the accepted structural model for the well known bitartrate on Cu(110) chiral system cannot account for the chiral segregation observed. Instead, we show that this strongly bound, chiral adsorbate changes its adsorption footprint in response to the local environment. The flexible adsorption geometry allows bitartrate to form stable homochiral trimer chains in which the central molecule restructures from a rectangular to an oblique footprint, breaking its internal hydrogen bonds in order to form strong intermolecular hydrogen bonds to neighbouring adsorbates...
March 2, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28251666/facile-synthesis-and-application-of-teicoplanin-modified-magnetic-microparticles-for-enantioseparation
#20
Huijuan Wang, Xuehan An, Xiaojuan Deng, Guosheng Ding
A facile, mild method for the preparation of teicoplanin (TE) modified Fe3 O4 microparticles (MPs) employing polydopamine (PDA) layer as a versatile secondary reaction platform was developed. The synthesized magnetic MPs (Fe3 O4 @PDA@TE) were characterized by various characterization techniques, such as TEM, zeta potential etc, to affirm the successful modification of TE to magnetic Fe3 O4 MPs. Using the as-synthesized materials as chiral adsorbents, efficient chiral separation of representative racemic compounds was successfully achieved...
March 2, 2017: Electrophoresis
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