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11.
Yi Zheng Ziqing Wang Gabrielle Lui Dborah Hirt Jean‐Marc Treluyer Sihem Benaboud Radia Aboura Ins Gana 《Biomedical chromatography : BMC》2019,33(5)
Levofloxacin, pefloxacin, ciprofloxacin and moxifloxacin are four fluoroquinolones used in the treatment of serious bacterial infections. The antibacterial activity of fluoroquinolones is concentration dependent. Therefore, therapeutic drug monitoring in daily clinical practice is warranted to ensure the therapy's efficacy and prevent bacterial resistance. The purpose of the present study was to develop a method using high‐pressure liquid chromatography with an ultraviolet detector for simultaneous quantification of these four fluoroquinolones in human plasma. A 50 μL aliquot of plasma was precipitated by 200 μL of methanol using gatifloxacin as internal standard. The chromatographic separation was performed on a Kinetex XB‐C18 column using a mobile phase composed of a mixture of orthophosphoric acid 0.4% (v/v), acetonitrile and methanol at a flow rate of 1.2 mL/min. Dual UV wavelength mode was used, with levofloxacin and moxifloxacin monitored at 293 nm, and pefloxacin and ciprofloxacin monitored at 280 nm. The calibration was linear over the ranges of 0.125–25 mg/L for levofloxacin, 0.1–20mg/L for moxifloxacin and 0.05‐10 mg/L for both pefloxacin and ciprofloxacin. Inter‐ and intra‐day trueness and precision were <13% for all the compounds under study. The proposed method was simple, reliable, cost‐effective and suitable for therapeutic drug monitoring or pharmacokinetics studies. 相似文献
12.
Jimmy Yuk Kristina L. McIntyre Christian Fischer Joshua Hicks Kimberly L. Colson Ed Lui Dan Brown John T. Arnason 《Analytical and bioanalytical chemistry》2013,405(13):4499-4509
The use of 1H-NMR-based metabolomics to distinguish and identify unique markers of five Ontario ginseng (Panax quinquefolius L.) landraces and two ginseng species (P. quinquefolius and P. ginseng) was evaluated. Three landraces (2, 3, and 5) were distinguished from one another in the principal component analysis (PCA) scores plot. Further analysis was conducted and specific discriminating metabolites from the PCA loadings were determined. Landraces 3 and 5 were distinguishable on the basis of a decreased NMR intensity in the methyl ginsenoside region, indicating decreased overall ginsenoside levels. In addition, landrace 5 was separated by an increased amount of sucrose relative to the rest of the landraces. Landrace 2 was separated from the rest of the landraces by the increased level of ginsenoside Rb1. The Ontario P. quinquefolius was also compared with Asian P. ginseng by PCA, and clear separation between the two groups was detected in the PCA scores plot. The PCA loadings plot and a t-test NMR difference plot were able to identify an increased level of maltose and a decreased level of sucrose in the Asian ginseng compared with the Ontario ginseng. An overall decrease of ginsenoside content, especially ginsenoside Rb1, was also detected in the Asian ginseng’s metabolic profile. This study demonstrates the potential of NMR-based metabolomics as a powerful high-throughput technique in distinguishing various closely related ginseng landraces and its ability to identify metabolic differences from Ontario and Asian ginseng. The results from this study will allow better understanding for quality assessment, species authentication, and the potential for developing a fully automated method for quality control. Figure
Principal component analysis scores and loadings plot for differentiating between closely-related ginseng landraces in Ontario, Canada 相似文献
13.
Xu-Feng Tan Li-Yong Yuan Chang-Ming Nie Kui Lui Zhi-Fang Chai Wei-Qun Shi 《Journal of Radioanalytical and Nuclear Chemistry》2014,302(1):281-288
Electrochemical behaviors of U(VI) in 1-butyl-3-methylimidazolium chloride (C4MimCl) with various water contents investigated by chronopotentiometry and cyclic voltammetry. The electrochemical reduction of U(VI) was identified to follow two processes: a lower valence intermediate U(V) was initially formed at the potential of ca. ?0.2 V(vs. Ag wire). Then, further deposition of UO2 was followed at around ?0.8 V. Little amount of water (1–4 wt%) in C4MimCl, however, has an effect on the U(VI) reduction by changing the current density of the redox reaction and the diffusion coefficient of U(VI) in C4MimCl. The deposited product by potentiostatic electrolysis on the surface of stainless steel electrode was characterized by the scanning electron microscopy (SEM), energy dispersive X-ray (EDX) and X-ray diffraction (XRD) methods. Although the electrodeposited black film was amorphous, the electrochemical reduced product of U(VI) can be still confirmed to be UO2 by XRD after the crystallization of the amorphous deposits at 1,073 K in nitrogen atmosphere. 相似文献
14.
本文对边界元方法中的各类积分根据其奇异性作分类,并对主值积分的收敛条件、变量替换等进行了讨论,又给出了变替换附加项显式。文中提供的主值积分配项消奇术在边界元方法中是有普遍意义的。 相似文献
15.
乙酸松油酯的合成研究 总被引:1,自引:0,他引:1
采用弱碱性无水碳酸钾作催化剂,结合真空精馏连续分离醋酸的工艺,由松油醇和醋酐合成了乙酸松油酯,摩尔得率达92.4%,经真空蒸馏含量达95.3%.该方法用于乙酸芳樟酯合成,产率也大于90%. 相似文献
16.
成对电解法制取葡萄糖酸和山梨醇 总被引:1,自引:0,他引:1
探讨了用葡萄糖成对电解氧化还原法制取葡萄糖酸和山梨醇的工艺条件,对直接电解法和间接电解法进行了研究比较,分析了它们的优缺点,以期打到实现工业化生产的途径。 相似文献
17.
刘福德 《天津理工大学学报》1994,(2)
本文测定了苯—正壬烷、苯—正十一烷、环已烷—正壬烷、环已烷—正十一烷、四氯化碳—正辛烷五个二元物系过量热容C,并与Flory理论对C的预测值进行了比较,得到了分子取向次序变化对C的贡献大小。结果发现Flory理论对C的预测值与C的实验值偏差很大,分子取向次序的破坏对C的贡献为负值。 相似文献
18.
对MCS-96单片机应用到智能仪表中进行了实质性的研究。根据红外检测纸张水分的特点,充分利用8098I/O接口灵活和运算能力强等优点,简化了硬件系统结构,提高了抗干扰能力,又在数据处理中采用参比技术、数字滤波、非线性处理等技术,使测量精度得以提高。 相似文献
19.
We have measured transient photoconductivity in functionalized pentacene molecular crystals using ultrafast optical pump-terahertz probe techniques. The single crystal samples were excited using 800 nm, 100 fs pulses, and the change in transmission of time-delayed, subpicosecond terahertz pulses was used to probe the photoconducting state over a temperature range from 10 to 300 K. A subpicosecond rise in photoconductivity is observed, suggesting that mobile carriers are a primary photoexcitation. At times longer than 4 ps, a power-law decay is observed consistent with dispersive transport. 相似文献
20.
本文考察了固体酸FeCl_2,AlCl_2,Fe_2(SO_4)_3,在羧酸与环氧化合物加成酯化反应的催化活性,并研究了反应的取向。用性质稳定的Fe_2(SO_4)_3为催化剂,合成了16种羧酸β-羟丙基酯,产率为50%~84%。 相似文献