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991.
Cheremina O Bachmakov I Neubert A Brune K Fromm MF Hinz B 《Biomedical chromatography : BMC》2005,19(10):777-782
Oxycodone (14-hydroxy-7,8-dihydrocodeinone) is a potent opioid receptor agonist. In the present study, a liquid-liquid extraction-based reversed-phase HPLC method with UV detection was validated and applied for the analysis of oxycodone and its major metabolite, noroxycodone, in human plasma. The analytes were separated using a mobile phase, consisting of acetonitrile and phosphate buffer (8:92, v/v) at a flow rate of 1 mL/min, and UV detection at 205 nm. The retention times for oxycodone, noroxycodone and codein (internal standard) were 14.7, 13.8 and 10.2 min, respectively. The validated quantitation range of the method was 2-100 ng/mL for oxycodone and 10-100 ng/mL for noroxycodone. The developed procedure was applied to assess the pharmacokinetics of oxycodone and its metabolite following administration of a single 20 mg oral dose of oxycodone hydrochloride to one healthy male volunteer. 相似文献
992.
Solid phase microextraction (SPME) then capillary gas chromatography with mass spectrometric detection have been used for determination of nine phenyl compounds in snow water in Beijing City. Headspace extraction with a fiber coated with 100 µm PDMS was used to extract the compounds. Extraction and desorption times were optimized at 8 and 2 min, respectively. Relative standard deviation (RSD) of the analytical method was found to be less than 5%. The linear range was wide and limits of detection were less than 5 ng mL−1 for the nine target analytes. Several phenyl compounds at ng mL−1 levels were detected in snow samples in Beijing, indicating the corresponding air pollution. 相似文献
993.
A series of symmetrical dialkyl ammonium salts, DCnX, has been prepared and characterized with respect to temperature and enthalpy of solid-solid phase transitions, temperature of melting, thermal stability as well as the reversibility of the phase transitions. The number of carbon atoms, Cn, was varied between 8 and 18 and as anions X halides, nitrate, chlorate, perchlorate and hydrogen sulphate had been chosen. In dependence on chain length and anion type transition temperatures from 20 to 100 °C were observed. Mass specific solid-solid transition enthalpies reach values of 185 J g−1, which makes this class of substances attractive for heat storage applications. The influence of anion type on the transition enthalpies is explained in terms of packing requirements, hydrogen bond network formation and contributions from hindered anion rotation. 相似文献
994.
995.
《Arabian Journal of Chemistry》2020,13(2):4082-4091
In present study, an investigation was carried out to develop and validate an analytical method for the selective extraction and determination of griseofulvin (GSF) from plasma samples. For this purpose, a rational approach was made to synthesize and characterize the surface molecularly imprinted polymers (SMIPs). The SMIPs were utilized as solid phase extraction (SPE) sorbents. The SMIPs were prepared by using GSF as template molecule on the surface of modified silica particles through a non-covalent technique. The particles demonstrated high adsorption capacity (119.1 µg/mL), fast adsorption equilibrium time (30 min) and good recognition selectivity for the template drug. The scanning electron microscopy and infrared spectroscopy were used to explain the structural and morphological characteristics of the SMIPs and surface non-imprinted polymers. The SPE method was combined with HPLC for plasma analysis. The method validation results demonstrated that the established method possessed good linearity for GSF ranging from 0.1 to 50 µg/mL (R2 = 0.997). The limit of detection for this method was 0.02 µg/mL for rat plasma samples. The recoveries of GSF from spiked plasma samples were (90.7–97.7%) and relative standard deviations were (0.9–4.5%). Moreover, the SMIPs as selective SPE sorbent can be reused more than 8 times which is a clear advantage over commercial SPE sorbents. Finally, the usefulness of the proposed strategy was assessed by extraction and detection of GSF in real rat plasma samples. 相似文献
996.
997.
A one-dimensional system of hard-rod particles with rotational-like internal degrees of freedom is considered. Particles interact with each other through the infinite-range, infinitely weak attractive Kac potential, and through a nearest-neighbor short-range potential. The latter depends also on the internal states of the interacting particles. Exact results for thermodynamic properties and for some correlation functions are obtained. It is found that the considered system exhibits several first-order transitions between phases with different rotational structure, i.e., with different ordering with respect to the internal degrees of freedom. The calculated equation of state seems to suggest that in the solutions of liquid-crystalline substances in neutral solvents there may exist regions in which the coefficient of thermal expansion is negative—an effect similar to that well known in liquid water. 相似文献
998.
999.
为了探寻电流脉冲泄流时,设备的接地是否有效可靠,用FDTD法分析了脉冲泄流时均一土壤、分层土壤及局部改善土壤的电导率对冲击接地阻抗(TGR)的影响。结果表明:大地电导率对冲击接地阻抗的影响很大;对均一土壤,TGR随大地电导率的增大而减小,大地电导率越大,TGR对接地体的埋深越不敏感。对分层土壤,接地体要埋在大地电导率大的土壤层中,且不要靠近交界面;局部改善大地导电性能对降低TGR效果明显,TGR对改善区域的体积非常敏感,而当电导率大于一定值时,大地电导率的再增加,对TGR的影响不明显。 相似文献
1000.
Titania (TiO2) photocatalysts, each embedded with one of six metals (Ag, Ce, Co, Fe, Mg, and Mn), were prepared using a simplified ultrasonic process. The characteristics of the prepared metal-embedded TiO2 (metal–TiO2) were determined using transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction spectroscopy, photoluminescence emission spectroscopy, UV–visible spectroscopy, and nitrogen adsorption–desorption. Except for Co–TiO2, the metal–TiO2 photocatalysts showed improved performance for the decomposition of gaseous benzene and toluene, which are two of the most problematic indoor air pollutants that can cause a variety of adverse health symptoms, under daylight lamp irradiation. Photocatalytic activity was greatest for the Mg–TiO2 sample, followed by, in order, the Ag–TiO2, Ce–TiO2, Fe–TiO2, Mn–TiO2, unmodified TiO2, and Co–TiO2 samples. Although Mg–TiO2 showed the least redshift in its light absorption and the highest electron–hole recombination rate among the metal–TiO2 photocatalysts, it yielded the highest photocatalytic activity, likely because of its increased adsorption capacity and anatase composition. The degradation of benzene and toluene over Mg–TiO2 improved as ultrasound treatment amplitude increased from 20 to 37 μm, then decreased gradually as amplitude was further increased to 49 μm. Degradation efficiency also improved as ultrasound operation time increased from 30 to 60 min, then decreased gradually as amplitude was further increased to 90 min. Overall, this process could be utilized to prepare metal–TiO2 photocatalysts with improved performance for the decomposition of gas phase pollutants under daylight lamp irradiation. 相似文献