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排序方式: 共有6813条查询结果,搜索用时 31 毫秒
1.
Inas A. Abdallah Sherin F. Hammad Alaa Bedair Mohamed A. Abdelaziz Neil D. Danielson Ahmed H. Elshafeey Fotouh R. Mansour 《Biomedical chromatography : BMC》2022,36(6):e5365
Favipiravir is a potential antiviral medication that has been recently licensed for Covid-19 treatment. In this work, a gadolinium-based magnetic ionic liquid was prepared and used as an extractant in dispersive liquid–liquid microextraction (DLLME) of favipiravir in human plasma. The high enriching ability of DLLME allowed the determination of favipiravir in real samples using HPLC/UV with sufficient sensitivity. The effects of several variables on extraction efficiency were investigated, including type of extractant, amount of extractant, type of disperser and disperser volume. The maximum enrichment was attained using 50 mg of the Gd-magnetic ionic liquid (MIL) and 150 μl of tetrahydrofuran. The Gd-based MIL could form a supramolecular assembly in the presence of tetrahydrofuran, which enhanced the extraction efficiency of favipiravir. The developed method was validated according to US Food and Drug Administration bioanalytical method validation guidelines. The coefficient of determination was 0.9999, for a linear concentration range of 25 to 1.0 × 105 ng/ml. The percentage recovery (accuracy) varied from 99.83 to 104.2%, with RSD values (precision) ranging from 4.07 to 11.84%. The total extraction time was about 12 min and the HPLC analysis time was 5 min. The method was simple, selective and sensitive for the determination of favipiravir in real human plasma. 相似文献
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Elnaz Marzi Khosrowshahi Behnaz Limuie Khosrowshahi Mir Ali Farajzadeh Abolghasem Jouyban Mustafa Tuzen Mohammad Reza Afshar Mogaddam Mahboob Nemati 《Biomedical chromatography : BMC》2022,36(7):e5371
A dispersive solid-phase extraction method based on a new sorbent has been performed on plasma and wastewater samples to determine metoprolol by high-performance liquid chromatography–tandem mass spectrometry. In this study, the analyte was adsorbed from the samples onto microcrystalline cellulose as a green and efficient sorbent and then eluted for use in the determination step. In the mass spectrometer, the analyte was detected in the positive mode and selectivity of the analysis was increased by sequential mass analysis through multiple reaction monitoring. All of the effective parameters in the extraction of metoprolol from plasma and wastewater were optimized. Under optimal conditions the method was linear in the ranges of 1–1,000 and 0.1–1,000 ng/ml in plasma and wastewater samples, respectively. The detection limits of the method were 0.30 and 0.03 ng/ml in plasma and wastewater samples, respectively. The data showed that the method provides low detection limit, wide linear range, good precision and high extraction recovery. Finally several plasma and wastewater samples were successfully analyzed using the method. The use of a small amount of a green and inexpensive sorbent and a low volume of plasma without the need for further pretreatment steps are the main advantages of the method. 相似文献
4.
A sensitive and efficient method for trace analysis of some phenolic compounds using simultaneous derivatization and air‐assisted liquid–liquid microextraction from human urine and plasma samples followed by gas chromatography–nitrogen phosphorous detection
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Mir Ali Farajzadeh Mohammad Reza Afshar Mogaddam Ali Akbar Alizadeh Nabil 《Biomedical chromatography : BMC》2015,29(12):1921-1931
In present study, a simultaneous derivatization and air‐assisted liquid–liquid microextraction method combined with gas chromatography–nitrogen phosphorous detection has been developed for the determination of some phenolic compounds in biological samples. The analytes are derivatized and extracted simultaneously by a fast reaction with 1‐flouro‐2,4‐dinitrobenzene under mild conditions. Under optimal conditions low limits of detection in the range of 0.05–0.34 ng mL?1 are achievable. The obtained extraction recoveries are between 84 and 97% and the relative standard deviations are less than 7.2% for intraday (n = 6) and interday (n = 4) precisions. The proposed method was demonstrated to be a simple and efficient method for the analysis of phenols in biological samples. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
5.
This review provides a comprehensive evaluation of solidified floating organic drop microextraction (SFODME) procedures for metal ions preconcentration and their contributions to green chemistry. In this article we focused on the modifications that have been performed in the recent years to improve this environmentally friendly procedure. Among the most important of these modifications are the inclusion of ultrasonic energy, vortex and air agitation to enhance the dispersion process. The article also discussed new challenges in the procedure by using more ecofriendly solvents as extractants such as ionic liquids, deep eutectic. and supramolecular solvents. The coupling of SFODME with solid phase extraction increases selectivity and efficiency of the preconcentration procedure. 相似文献
6.
Alexander J. Marshall 《Analytica chimica acta》2004,527(1):13-20
Holographic sensors for monitoring ionic strength have been fabricated from charged sulphonate and quaternary ammonium monomers, incorporated into thin, polymeric hydrogel films which were transformed into volume holograms. The diffraction wavelength or reflected colour of the holograms was used to characterise their swelling or de-swelling behaviour as a function of ionic strength in various media. The effects of co-monomer structure, buffer composition, ion composition, pH and temperature were evaluated, whilst the reversibility and reproducibility of the sensor was also assessed. An acrylamide-based hologram containing equal molar amounts of negatively and positively charged monomers was shown to be able to quantify ionic strength independent of the identity of the ionic species present in the test solution. The sensor was fully reversible, free of hysteresis and exhibited little response to pH between 3 and 9 and temperature within the range 20-45 °C. The system was successfully used to quantify the ionic strength of milk solutions, which contain a complex mixture of ions and biological components. 相似文献
7.
空心阴极灯激发的微波等离子体炬原子/离子荧光光谱研究--钙的原子/离子荧光光谱 总被引:2,自引:0,他引:2
用强短脉冲供电技术的空心阴极灯作激发源、微波等离子体炬作原子/离子化器,建立了原子/离子荧光光谱实验装置。详细研究了微波等离子体功率、观察高度、空心阴极灯电流等因素对原子/离子荧光信号强度的影响,测量了系统对Ca的原子/离子荧光光谱的检出限。 相似文献
8.
《Journal of solid state chemistry》2004,177(7):2366-2372
Proton exchange reactions have been performed on tetragonal tungsten bronze-like NaNbWO6 by using nitric acid as an exchanging agent. The characterization of the exchange reaction products has been made by means of chemical analysis, X-ray diffraction, thermal analysis, and IR spectroscopy. The exchange reaction takes place topotactically and the following formula is proposed for the obtained phase of variable composition: Na1−xHxNbWO6·yH2O (0<x?0.46 and 0?y?0.12). Impedance spectroscopy on the present proton exchanged samples indicated that these samples behaved as solid electrolytes under high humidity. As an example, the compound with the composition Na0.68H0.32NbWO6·0.1 H2O exhibits ionic conductivity of 8×10−3 and 1×10−2 S cm−1 at 70°C and 90°C, respectively. 相似文献
9.
A room temperature ionic liquid, 1-pentyl-3-methylimidazolium bromide, [pmIm]Br efficiently catalyzes Michael addition of thiols and diethyl dithiophosphate to a variety of conjugated alkenes such as α,β-unsaturated carbonyl compounds, carboxylic esters, nitriles and chalcones without requiring any other organic solvent and catalyst. The ionic liquid can be recycled for subsequent reactions without any appreciable loss of efficiency. 相似文献
10.
Xanthenediones derivatives have attracted considerable interests in recent times because they constitute a structural unit in a number of natural products1 and have been used as versatile synthons due to the inherent reactivity of the inbuilt pyran ring2. The conventional syntheses of xanthenediones were acid or base catalyzed condensation of appropriate active methylene carbonyl compounds with aldehydes3. However, many of these procedures involved longer reaction times,low yields and side reactions of aldehydes. In recent years, room temperature ionic liquids (RTILs) have been used as novel green reaction media4. Considering that InCl3 is an efficient Lewis acid catalyst used in promoting many organic reactions, especially in several condensation processes, we herein wish to report a very simple and green method for the preparation of poly-hydrogenated xanthenediones through InCl3·4H2O promoted cascade reaction of aldehydes and 5,5-dimethyl-l,3-cyclohexanedione in ionic liquid,1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]). The preparative process presented here is operationally simple, environmentally benign and has the advantage of enhanced atom utilization. Furthermore, the solvent and the catalyst used can be recovered easily and reused efficiently. 相似文献