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121.
Summary A clean method without use of organic solvents has been developed for isolation and high-performance liquid chromatographic
(HPLC) determination of oxytetracycline (OTC) and sulphadimidine (SDD) in cow's milk. Isolation is rapid and simple—homogenization
with an inorganic acid solution by means of a handy ultrasonic homogenizer, which is easy-to-use and portable, followed by
centrifugation. Reversed-phase HPLC was performed on a C4 column, with 1.25 mmol L−1 succinic acid solution as mobile phase, and identification was by means of a photodiode-array detector. Separation of the
analytes was achieved in less than 8 min. Significant linearity was established over the concentration range of 0.1–1.0 μg
mL−1 for both target compounds (r>0.99,P<0.01). Average recoveries of OTC and SDD (each spiked at 0.1–1.0 μg mL−1) were ≥88.8, and inter- and intra-assay variability was ≤2.8%. The total time required for analysis of one sample was <20
min. The limits of quantitation of the method (μg mL−1 in milk) were 0.044 for OTC and 0.023 for SDD. No organic solvent was used at any stage of the analysis. 相似文献
122.
123.
Jayeon Hong Sangsub Kim Gyurim Park Yongmoon Lee Hyungchae Kim Sungjin Kim Tae-Woo Lee Changsoon Kim Youngmin You 《Chemical science》2021,12(25):8668
Polymer electroluminescence devices producing circularly polarized luminescence (CP PLEDs) have valuable photonic applications. The fabrication of a CP PLED requires a polymer host that provides the appropriate chiral environment around the emitting dopant. However, chemical strategies for the design of chiral polymer hosts remain underdeveloped. We have developed new polymer hosts for CP PLED applications. These polymers were prepared through a free-radical polymerization of 3-vinylcarbazole with a chiral N-alkyl unit. This chiral unit forces the carbazole repeat units to form mutually helical half-sandwich conformers with preferred (P)-helical sense along the polymer main chain. Electronic circular dichroism measurements demonstrate the occurrence of chirality transfer from chiral monomers to achiral monomers during chain growth. The (P)-helical-sense-enriched polymer interacts diastereoselectively with an enantiomeric pair of new phosphorescent (R)- and (S)-dopants. The magnitude of the Kuhn dissymmetry factor (gabs) for the (P)-helically-enriched polymer film doped with the (R)-dopant was found to be one order of magnitude higher than that of the film doped with the (S)-dopant. Photoluminescence dissymmetry factors (gPL) of the order of 10−3 were recorded for the doped films, but the magnitude of diastereomeric enhancement decreased to that of gabs. The chiral polymer host permits faster energy transfer to the phosphorescent dopants than the achiral polymer host. Our photophysical and morphological investigations indicate that the acceleration in the chiral polymer host is due to its longer Förster radius and improved compatibility with the dopants. Finally, multilayer CP PLEDs were fabricated and evaluated. Devices based on the chiral polymer host with the (R)- and (S)-dopants exhibit electroluminescence dissymmetry factors (gEL) of 1.09 × 10−4 and −1.02 × 10−4 at a wavelength of 540 nm, respectively. Although challenges remain in the development of polymer hosts for CP PLEDs, our research demonstrates that chiroptical performances can be amplified by using chiral polymer hosts.Polymer electroluminescence devices producing circularly polarized luminescence (CP PLEDs) have valuable photonic applications. 相似文献
124.
125.
A novel homochiral 3D metal-organic framework [CdL2(H2O)2][ClO4]2.2DMF.3EtOH.5/3H2O, 1, (L =(R)-6,6-dichloro-2,2-diethoxy-1,1-binaphthyl-4,4-bipyridine) exhibits an unprecedented 4-connected network topology owing to the cis- configuration of the Cd coordination and possesses permanent porosity as demonstrated by TGA, XRPD, and CO2 adsorption isotherm studies. 相似文献
126.
Summary A sensitive LC method for the detection of amino acids and oligopeptides with pre-column fluorescence derivatization has been
developed. Glycine, glycylglycine, triglycine, glutathione, glutamic acid, and cysteine were separated on a reversed-phase
C18 column with methanol-water-triethylamine eluent, derivatization and chromatographic conditions were optimized. The six derivatives
were eluted in 20 min with good reproducibility. The relative standard derviations (n=6) at an analytical concentration of
2×10−6 M are <5%. Detection limits (signal-to-noise ratio=3) for the six derivatives are 23–68 fmol. 相似文献
127.
128.
Two new Schiff bases (SMPDH and SBPDH) of S-methyl- and S-benzyl-dithiocarbazate with 2-pyridinecarboxaldehyde N-oxide were prepared and confirmed by elemental analyses and IR spectra. Four copper(II) complexes of the above two Schiff base ligands with imidazole and pyridine were obtained and characterized spectroscopically. The crystal structure of [Cu(SMPD)ImH]ClO4 was determined by X-ray diffraction analysis. The geometry of the copper atoms in these complexes is square planar with an unsymmetrical environment. 相似文献
129.
A new catalyst system for the synthesis of alpha-aryl-substituted nitriles is reported. The bicyclic triaminophosphine P(i-BuNCH(2)CH(2))(3)N (1b) serves as an efficient and versatile ligand for the palladium-catalyzed direct alpha-arylation of nitriles with aryl bromides. Using ligand 1b, ethyl cyanoacetate and primary as well as secondary nitriles are efficiently coupled with a wide variety of aryl bromides possessing electron-rich, electron-poor, electron-neutral, and sterically hindered groups. 相似文献
130.
A rapid capillary electrophoresis method for the separation of five natural pharmacologically active compounds from extracted Rhodiola, namely salidroside, tyrosol, rhodionin, gallic acid and ethyl gallate has been developed. The separation of five natural pharmacologically active compounds was carried out in a fused-silica capillary with 14 mM boric acid, 30 mM SDS and 2.5% acetonitrile, adjusted to pH 10.7 with NaOH. Applied potential was 21kV. The temperature of the capillary was maintained at 25 °C by the instrument thermostating system, with the correlation coefficients of 0.9805–0.9989 for migration time, and relative standards of < 3.52% for peak areas. The established method is rapid and reproducible for the separation of five natural pharmacologically compounds from extracts of Rhodiola with satisfactory results. 相似文献