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Chiral separation

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https://www.readbyqxmd.com/read/29785784/enantioselective-micellar-electrokinetic-chromatography-of-dl-amino-acids-using-1-9-fluorenyl-ethyl-chloroformate-derivatization-and-uv-induced-fluorescence-detection
#1
Amir Prior, Erik van de Nieuwenhuijzen, Gerhardus J de Jong, Govert W Somsen
Chiral analysis of dl-amino acids was achieved by micellar electrokinetic chromatography coupled with UV-excited fluorescence detection. The fluorescent reagent (+)-1-(9-fluorenyl)ethyl chloroformate was employed as chiral amino acid derivatizing agent and sodium dodecyl sulfate served as pseudo-stationary phase for separating the formed amino acid diastereomers. Sensitive analysis of (+)-1-(9-fluorenyl)ethyl chloroformate-amino acids was achieved applying a xenon-mercury lamp for ultraviolet excitation, and a spectrograph and charge-coupled device for wavelength-resolved emission detection...
May 22, 2018: Journal of Separation Science
https://www.readbyqxmd.com/read/29782664/stereoselective-hplc-separation-of-alvimopan-on-cellulose-based-immobilized-polysaccharide-as-a-chiral-stationary-phase
#2
Nitin H Dhekale, Dattatray B Gunjal, Anil H Gore, Yagnakirankumar Komaravolu, K Hima Bindu, Govind B Kolekar
Chiral separation by normal phase high performance liquid chromatography is one of the most powerful technique to quantify the chiral purity of the compounds. In this study, a novel, simple, and specific analytical method was proposed to ascertain the chiral purity of alvimopan (ALV). The normal phase HPLC method was developed based on cellulose tris (3,5-dichlorophenylcarbamate) stationary phase. The separation of ALV isomers achieved by using column CHIRALPAK IC (250 × 4.6 mm, 5 μm), mobile phase n-hexane: isopropyl alcohol: ethanol: diethylamine (650:200:150:5 v/v), column oven temperature 30°C, flow rate 1...
May 21, 2018: Chirality
https://www.readbyqxmd.com/read/29775308/piperidine-alkaloids-with-diverse-skeletons-from-anacyclus-pyrethrum
#3
Qi-Bin Chen, Jie Gao, Guo-An Zou, Xue-Lei Xin, Haji Akber Aisa
Fifteen new piperidine derivatives, pyracyclumines A-J (1-10), including five pairs of enantiomers, (+)-1/(-)-1 to (+)-5/(-)-5, together with three known compounds, agrocybenine (11), 4,6,6-trimethyl-5,6-dihydro-2(1 H)-pyridone (12), and 3,5,5-trimethyl-1,5-dihydro-2 H-pyrrol-2-one (13), were isolated from the roots of Anacyclus pyrethrum. Pyracyclumines A, B, and H (1, 2, and 8) possess a novel 6/5/6/6 dimeric piperidine skeleton, a unique 6/5/6 dimeric piperidine skeleton, and a 1,4,6-triazaindan skeleton, respectively...
May 18, 2018: Journal of Natural Products
https://www.readbyqxmd.com/read/29775209/comparative-studies-of-immobilized-chiral-stationary-phases-based-on-polysaccharide-derivatives-for-enantiomeric-separation-of-fifteen-azole-compounds
#4
Bolin Zhu, Miaoduo Deng, Yaqi Yao, Jia Yu, Qing Li
Immobilized polysaccharide-based columns showed excellent enantioselectivity in normal phase separation mode. In this work, enantioseparation abilities of four immobilized polysaccharide-derived chiral stationary phases (Chiralpak IA, Chiralpak IB, Chiralpak IC and Chiralpak ID) toward fifteen azole compounds were evaluated. Separation was carried out using n-hexane as mobile phase with ethanol, 1-propanol, 1-butanol and 2-propanol as modifiers. And twelve compounds have achieved baseline separation with the resolutions ranging between 2...
May 18, 2018: Electrophoresis
https://www.readbyqxmd.com/read/29774905/dual-emissions-and-thermochromic-luminescences-of-isomorphic-chiral-twofold-interpenetrated-3-d-nets-built-from-i-1-o-2-type-hybrid-inorganic-organic-frameworks-of-nh-2-ch-3-2-3-pb-2-x-3-bdc-2-x-br-i
#5
Shao-Xian Liu, Guo-Jun Yuan, Lu Zhai, Lifeng Wang, Hong-Bin Luo, Xiao-Ming Ren
Two pairs of MOF-based hybrid enantiomorphs, [NH2(CH3)2]3[Pb2X3(BDC)2] (H2BDC = 1,4-benzenedicarboxylic acid, X = Br or I), have been synthesized using the solvothermal reaction and then manually separated, which are labeled as 1a/1b (X = Br) and 2a/2b (X = I). The isomorphic 1a and 2a crystallize in tetragonal space group P43212, and the isomorphic 1b and 2b in the enantiomorphic space group P41212. Twofold interpenetrated three-dimensional (3-D) networks were built from two sets of equivalent I1O2 type hybrid inorganic-organic frameworks in 1a/1b and 2a/2b...
May 18, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/29770829/mixing-and-demixing-of-binary-mixtures-of-polar-chiral-active-particles
#6
Bao-Quan Ai, Zhi-Gang Shao, Wei-Rong Zhong
We study a binary mixture of polar chiral (counterclockwise or clockwise) active particles in a two-dimensional box with periodic boundary conditions. Besides the excluded volume interactions between particles, the particles are also subjected to the polar velocity alignment. From the extensive Brownian dynamics simulations, it is found that the particle configuration (mixing or demixing) is determined by the competition between the chirality difference and the polar velocity alignment. When the chirality difference competes with the polar velocity alignment, the clockwise particles aggregate in one cluster and the counterclockwise particles aggregate in the other cluster; thus, the particles are demixed and can be separated...
May 17, 2018: Soft Matter
https://www.readbyqxmd.com/read/29770554/chiral-recognition-and-separation-by-chirality-enriched-metal-organic-frameworks
#7
Saikat Das, Shixian Xu, Teng Ben, Shilun Qiu
Endowed with chiral channels and pores, chiral metal-organic frameworks (MOFs) are considerably useful; however, they remain a challenge given most chiral building blocks are expensive. Albeit induced chiral MOFs have been reported to mitigate this shortcoming, no study providing evidence for the enantiomeric excess (ee) value of induced chiral MOFs has been reported yet. We herein describe the first study on the efficiency of chiral induction in MOFs using inexpensive achiral building blocks and fully recoverable chiral dopants to control the handedness of racemic MOFs yielding chirality-enriched MOFs with accessible pores...
May 16, 2018: Angewandte Chemie
https://www.readbyqxmd.com/read/29768665/chiral-separation-of-isoxanthohumol-and-8-prenylnaringenin-in-beer-hop-pellets-and-hops-by-hplc-with-chiral-columns
#8
Hyuga Moriya, Sohei Tanaka, Yukari Iida, Satomi Kitagawa, Sen-Ichi Aizawa, Atsushi Taga, Hiroyuki Terashima, Atsushi Yamamoto, Shuji Kodama
Xanthohumol, isoxanthohumol, and 8-prenylnaringenin in beer, hop, and hop pellet samples were analyzed by HPLC using InertSustain phenyl column and the mobile phase containing 40% methanol and 12% 2-propanol. Fractions of isoxanthohumol and 8-prenylnaringenin obtained by the above HPLC were separately collected. Isoxanthohumol and 8-prenylnaringenin were enantioseparated by HPLC using Chiralcel OD-H column with a mobile phase composed of hexane/ethanol (90/10, v/v) and Chiralpak AD-RH column with a mobile phase composed of methanol/2-propanol/water (40/20/40, v/v/v), respectively...
May 16, 2018: Biomedical Chromatography: BMC
https://www.readbyqxmd.com/read/29765079/determination-of-flumequine-enantiomers-and-7-hydroxyflumequine-in-water-and-sediment-by-chiral-hplc-coupled-with-hybrid-quadrupole-time-of-flight-mass-spectrometer
#9
Moyong Xue, Yuchang Qin, Xu Gu, Junguo Li, Yunfeng Gao, Xiaowei Yang, Ting Yao, Zhen Zhao
A liquid chromatography-tandem mass spectrometric (LC-MS/MS) method for simultaneous enantiomeric analysis of flumequine and its metabolite 7-hydroxyflumequine in water and sediment had been developed based on the separation method. Sediment samples were extracted with ACN and EDTA-Mcllvaine buffer solution (40:60, v/v) then were enriched and cleaned-up by Cleanert PEP solid-phase extraction cartridges. The extract solvent, solid cartridges, mobile phase ratios, and chiral separation column were all optimized to reach high sensitivity and selectivity, good peak shape, and satisfactory resolution...
May 15, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29762128/collective-excitations-in-weyl-semimetals-in-the-hydrodynamic-regime
#10
Pavlo O Sukhachov, E V Gorbar, Igor A Shovkovy, V A Miransky
The spectrum of collective excitations in Weyl materials is studied by using a consistent hydrodynamics. The corresponding framework includes the vortical and chiral anomaly effects, as well as the dependence on the separations between the Weyl nodes in energy b<sub>0</sub> and momentum <b>b</b>. The latter are introduced via the Chern--Simons contributions to the electric current and charge densities in Maxwell's equations. It is found that, even in the absence of a background magnetic field, certain collective excitations (e...
May 15, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/29761177/enantioselective-separation-of-rs-mandelic-acid-using-%C3%AE-cyclodextrin-modified-fe-3-o-4-sio-2-au-microspheres
#11
Xiaojuan Deng, Wenbin Li, Guosheng Ding, Xiaoping Chen
Chiral magnetic microspheres show great potential in direct enantioseparation. Herein novel chiral magnetic microspheres were prepared by self-assembling β-cyclodextrin on magnetic Fe3O4@SiO2/Au composite microspheres. The prepared materials were characterized by transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), vibrating sample magnetometry (VSM) and Fourier transform infrared spectroscopy (FTIR). The results showed that the functional microspheres have a three-ply structure and high saturation magnetization...
May 15, 2018: Analyst
https://www.readbyqxmd.com/read/29759647/fundamental-aspects-of-field-amplified-electrokinetic-injection-of-cations-for-enantioselective-capillary-electrophoresis-with-sulfated-cyclodextrins-as-selectors
#12
Jozef Šesták, Regula Theurillat, Friederike A Sandbaumhüter, Wolfgang Thormann
Head-column field-amplified sample stacking of cations from a low conductivity sample followed by enantiomeric separation using negatively charged chiral selectors was studied experimentally and with computer simulation. Aspects investigated include the direct electrokinetic injection of the analytes into the background electrolyte, the use of a selector free buffer plug, the contribution of complexation within the buffer plug and the application of an additional water plug between sample and buffer plug. Attention was paid for changes of ionic strength which is known to have a significant impact on complexation and thus effective mobility...
May 9, 2018: Journal of Chromatography. A
https://www.readbyqxmd.com/read/29759645/complementary-enantioselectivity-profiles-of-chiral-cinchonan-carbamate-selectors-with-distinct-carbamate-residues-and-their-implementation-in-enantioselective-two-dimensional-high-performance-liquid-chromatography-of-amino-acids
#13
Ulrich Woiwode, Martina Ferri, Norbert M Maier, Wolfgang Lindner, Michael Lämmerhofer
A cardinal requirement for effective 2D-HPLC separations is sufficient complementarity in the retention profiles of first and second dimension separations. It is shown that retention and enantioselectivity of chiral selectors derived from cinchona alkaloids can be conveniently modulated by structural variation of the carbamate residue of the quinine/quinidine carbamate ligand of such chiral stationary phases (CSP). A variety of aliphatic and aromatic residues have been tested in comparison to non-carbamoylated quinine CSP...
April 27, 2018: Journal of Chromatography. A
https://www.readbyqxmd.com/read/29759222/a-high-performance-chiral-selector-derived-from-chitosan-p-methylbenzylurea-for-efficient-enantiomer-separation
#14
Sheng Tang, Xiaomeng Mei, Wei Chen, Shao-Hua Huang, Zheng-Wu Bai
N-Methoxycarbonyl chitosan was prepared by selectively modifying the amino group at the 2-position of chitosan with methyl chloroformate, which was further functionalized with p-methylbenzylamine to produce chitosan (p-methylbenzylurea). Then, the hydroxyl groups at the 3- and 6-positions of the glucose skeleton were modified with various phenyl isocyanates, affording a series of chitosan 3,6-bis(arylcarbamate)-2-(p-methylbenzylurea)s, which were characterized and proposed as chiral selectors for enantiomer separation...
August 1, 2018: Talanta
https://www.readbyqxmd.com/read/29759208/polarity-tuned-perphenylcarbamoylated-cyclodextrin-separation-materials-for-achiral-and-chiral-differentiation
#15
Xiaoxuan Li, Jia Li, Qing Kang, Yong Wang
Phenylcarbamoyls are known to remarkably accentuate cyclodextrin's enantioselectivities. In this work, by inducing electron-donating methoxyl or electron-withdrawing bromine/trifluoromethyl moieties, three novel cyclodextrin enantioseparation materials including per(4-trifluoromethoxy) phenylcarbamoylated-β-CD CSP (CSP1), per(4-bromo)phenylcarbamoylated-β-CD CSP (CSP2) and per(4-methoxy)phenylcarbamoylated-β-CD CSP (CSP3) were prepared via thiol-ene click chemistry. The polarity tuning decorations are found to significantly influence the CSPs' achiral and chiral separation performance...
August 1, 2018: Talanta
https://www.readbyqxmd.com/read/29758522/flavonoid-alkaloids-from-scutellaria-moniliorrhiza-with-anti-inflammatory-activities-and-inhibitory-activities-against-aldose-reductase
#16
Qing-Tong Han, Yan Ren, Gui-Sheng Li, Kang-Lin Xiang, Sheng-Jun Dai
Four undescribed flavonoid alkaloids, as two pairs of enantiomers, were initially isolated as a racemate from the whole plant of Scutellaria moniliorrhiza. By means of chiral HPLC, four isomers, named scumonilines A-D, were successfully separated, and their chemical structures including absolute configurations were established by mass as well as NMR spectroscopy and CD technique. In vitro, four flavonoid alkaloids showed anti-inflammatory activities, with IC50 values against the release of β-glucuronidase from polymorphonuclear leukocytes of rats being in the range 5...
May 11, 2018: Phytochemistry
https://www.readbyqxmd.com/read/29754482/effect-of-anisotropy-of-cellulose-nanocrystal-suspensions-on-stratification-domain-structure-formation-and-structural-colors
#17
Konrad W Klockars, Blaise L Tardy, Maryam Borghei, Anurodh Tripathi, Luiz Guillherme Garcia Greca, Orlando J Rojas
Outstanding optical and mechanical properties can be obtained from hierarchical assemblies of nanoparticles. Herein, the formation of helically-ordered, chiral nematic films obtained from aqueous suspensions of cellulose nanocrystals (CNCs) were studied as a function of the initial suspension state. Specifically, nanoparticle organization and the structural colors displayed by the resultant dry films were investigated as a function of the anisotropic volume fraction (AVF), which depended on the initial CNC concentration and equilibration time...
May 12, 2018: Biomacromolecules
https://www.readbyqxmd.com/read/29754067/enantiomeric-impurity-analysis-using-circular-dichroism-spectroscopy-with-united-states-pharmacopeia-liquid-chromatographic-methods
#18
Douglas Kirkpatrick, Margaret Fain, Jingyue Yang, Michael Trehy
Over 300 chiral drug substances lack official United States Pharmacopeia (USP) methods for the enantiomeric purity determination. Because enantiomeric analysis typically requires specialized methods for each drug compound, developing protocols for each of these 300+ substances would be an expensive and laborious endeavor. Alternatively, if a detector capable of determining the enantiomeric composition without chiral separation could be used with certain drug compounds, this could be implemented relatively rapidly into official testing monographs...
April 24, 2018: Journal of Pharmaceutical and Biomedical Analysis
https://www.readbyqxmd.com/read/29754062/enantioselective-fractionation-of-fluoroquinolones-in-the-aqueous-environment-using-chiral-liquid-chromatography-coupled-with-tandem-mass-spectrometry
#19
Erika Castrignanò, Andrew M Kannan, Edward J Feil, Barbara Kasprzyk-Hordern
This paper aims to examine the multiresidue enantiomeric profiling of (fluoro)quinolones and their metabolites in solid and liquid environmental matrices using chiral HPLC-MS/MS method and a CHIRALCEL® OZ-RH column. Simultaneous chiral separation was obtained for chiral ofloxacin and its main metabolites ofloxacin-N-oxide and desmethyl-ofloxacin; moxifloxacin; the prodrug prulifloxacin and its active compound ulifloxacin; flumequine; nadifloxacin and R-(+)-besifloxacin. Achiral antibiotics (ciprofloxacin, norfloxacin and nalidixic acid) were also included in the method to enable the analysis of all targeted quinolones within one analytical run...
May 4, 2018: Chemosphere
https://www.readbyqxmd.com/read/29752732/hplc-ecd-and-tddft-ecd-study-of-hexahydropyrrolo-1-2-a-quinoline-derivatives
#20
László Tóth, Attila Mándi, Dániel Váradi, Tibor Kovács, Anna Szabados, Attila Kiss-Szikszai, Qi Gong, Haiyan Zhang, Péter Mátyus, Sándor Antus, Tibor Kurtán
Synthesis of racemic hexahydropyrrolo[1,2-a]quinoline derivatives (1-8) was performed by utilizing the Knoevenagel-[1,5]-hydride shift-cyclization domino reaction. Separation of the enantiomers of the chiral products (1-8) was carried out by chiral high-performance liquid chromatography, and online high-performance liquid chromatography-electronic circular dichroism (ECD) spectra were recorded to elucidate the absolute configuration by comparing the experimental and time-dependent density functional theory-ECD spectra obtained at various theoretical levels...
May 12, 2018: Chirality
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