Quantification of complanatoside A in rat plasma using LC‐MS/MS and its application to a pharmacokinetic study

Complanatoside A is a flavonol glycoside isolated from Astragalus complanatus, and currently it is used as a quality control index for A. complanatus in the 2010 edition of the Chinese Pharmacopoeia. For the first time, a simple and sensitive LC‐MS/MS method was developed for the determination of complanatoside A in rat plasma over the range of 2.3–575 ng/mL. Complanatoside A was extracted from plasma by a protein precipitation procedure, separated by LC and detected by MS/MS in positive electrospray ionization mode. The method was validated for selectivity, carryover, sensitivity, linearity, extraction recovery, matrix effect, accuracy, precision and stability studies. The lower limit of quantification was established at 2.3 ng/mL. Intra‐ and inter‐day precisions (LLOQ, low‐QC, med‐QC and high‐QC) were <7.9%, and accuracies were between 94.0 and 105.1%. Matrix effect was acceptable (97.9–103.0%) and extraction recovery was reproducible (88.5–94.4%). Complanatoside A was stable in the investigated conditions. The method was applied to the pharmacokinetics of complanatoside A in rats. Copyright © 2015 John Wiley & Sons, Ltd.     

Analysis and Fate of Dibenzothiophene Derivatives in the Marine Environment

Abstract

Dibenzothiophene (DBT) and related methylated derivatives are known to be among the most persistent and probably the most toxic PAH in the marine environment. Their analysis and their fate by photo-oxidation and biodegradation were studied.

The methylated DBT isomers, provided that they are resolved by high resolution GC, were used as organic markers of oil pollution in oysters. The determination of the relative distribution of the four monomethyl DBT allowed to characterize the source of pollution in an oyster-area in the North Brittany (France).

The fate of methylated DBT compounds was studied in a controlled sea-water enclosure where Arabian light oil was spilled. Analysis of the weathered oil showed that: (i) oil was degraded by photo-oxidation at a rate of 0.004% day; (ii) the half-lives of photolysis of methylated DBT was dependent upon the number of methyl groups on the aromatic nucleus: 8 days for DBT, 20 days for methyl-1 DBT and more than 2 years for trimethylated DBT. Compounds solubilized in the water column were identified as methyl-substituted dibenzothiophene sulfoxides and sulfones by HPLC with synchrofluorescence and GC-flame photometric detection.

The metabolic pathway of DBT was established in vitro. Rat microsomes transformed this substrate to DBT-5-oxide and subsequently to DBT-5-dioxide. Such an enzymatic S-oxidation was shown to be principally Cytochrome-P-450 dependent. It is suggested that the mixed-function oxidase (MFO) activity of marine species could be evaluated by this S-oxidation test in addition to the usual aryl hydrocarbon hydroxylase.     

Novel conjugated nanoporous alkynyl metalloporphyrin framework as effective catalyst for oxidation of toluene with molecular oxygen

A porous alkynylporphyrin conjugated organic polymer (MnE‐TPP) was synthesized by Sonogashira coupling reaction with Mn(II) 5,10,15,20‐tetrakis(4′‐ethynylphenyl)porphyrin and Mn(II) 5,10,15,20‐tetrakis(4′‐bromophenyl)porphyrin as building blocks. The polymer was characterized using nitrogen adsorption–desorption isotherms, field‐emission scanning electron microscopy, high‐resolution transmission electron microscopy, Fourier transform infrared and UV–visible spectroscopies, X‐ray diffraction, thermogravimetry and inductively coupled plasma atomic emission spectrometry. The electrochemical behaviors of MnE‐TPP were investigated by cyclic voltammetry. MnE‐TPP was developed as a heterogeneous catalyst for the activation of molecular oxygen to oxidize toluene under mild conditions. The selectivity of total benzaldehyde and benzyl alcohol remained above 70.0% with a conversion of toluene up to 10.2%. The turnover number was as high as 13 653. Also, MnE‐TPP remained structurally stable and the toluene conversion rate hardly decreased after 5 h of reaction and five cycles of reuse.     

Fervent Hype behind Magnesium Batteries: An Open Call to Synthetic Chemists—Electrolytes and Cathodes Needed

Magnesium metal is a superior anode which has double the volumetric capacity of lithium metal and has a negative reduction potential of −2.37 V vs. the standard hydrogen electrode. A major benefit of magnesium is the apparent lack of dendrite formation during charging which is one of the crucial concerns of using a lithium metal anode. In this Review, we highlight the foremost research in the development of electrolytes and cathodes and discuss some of the significant challenges which must be overcome in realizing a practical magnesium battery.     

Molecularly imprinted polymer-sol-gel tablet toward micro-solid phase extraction: I. Determination of methadone in human plasma utilizing liquid chromatography–tandem mass spectrometry

In the present work molecularly imprinted sol-gel tablet (MIP-Tablet) was prepared. The MIP-sol-gel was prepared as a thin layer on polyethylene material in a tablet form. Methadone-d₉ was selected as the template and 3-(propylmethacrylate)-trimethoxysilane was used as precursor. MIP-Tablet was applied for micro-solid phase extraction (μ-SPE). The MIP-Tablet was used for the determination of methadone in human plasma samples utilizing liquid chromatography-tandem mass spectrometry; and each tablet could be used twenty times. The extraction time was 10 min while desorption time was 6 min. Factors affecting the extraction efficiency such as desorption solvents, sample pH, salt addition, extraction time, desorption time and adsorption capacity were investigated. The calibration curves were obtained within the range of 5–5000 ng/mL using methadone in human plasma samples. The coefficients of determination (r²) values were ≥0.999 for all runs and the extraction recovery was >80%. The accuracy values for quality control samples varied from +3.6 to +9.7% and the inter-day precision (RSD %) values were ranged from 5.0 to 8.0%. The limit of detection was 1.0 ng/mL and the lower limit of quantification was 5 ng/mL utilizing methadone in human plasma samples.     

Elastic Capacitor Electrode Based on Carbon‐embedded Polymer Matrix

AC impedance and voltammetry investigations revealed strong effect of the electrode composition on its machanical and electrical properties and led to its optimization in a CNT‐PVA‐PEG‐SiO₂‐KCl_aq system with good elasticity and excellent electrochemical stability. The uniform distribution of SiO₂ and carbon in the polymer fraction was confirmed by SEM imaging. This morphology facilitates retaining water and flexibility of films. An improvement of mass transport in the capacitor electrode as compared to a pure electrolyte was justified based on analysis of the diffusion resistance. The specific capacitance of the electrode and symmetrical capacitor cell is in the mF range and is suitable power system for microelectronic components.     

Characterization of interactions of metal‐containing nanoparticles with biomolecules by CE: An update (2012–2016)

The methodological developments and applications of CE related to studying biotransformations of metal‐based nanoscale particles of impending medicinal use are overviewed. This is an update to a previous review article (Aleksenko, S. S., Shmykov, A. Y., Oszwałdowski, S., Timerbaev, A. R., Metallomics 2012, 4 , 1141–1148) and it covers the research papers published within the last five years. As was anticipated in that review, CE can now be seen as a customary technique in the analysis of biomolecular interactions that exert an impact on the mechanism of action of nanoparticles, comprising metabolism, delivery, cell processing, and targeting. Different ways by which the CE method is applied for such monitoring, including conjugation mode, sample preparation, separation, and detection, are critically assessed. Special emphasis is put on examinations using inductively coupled plasma MS detection recent advent of which to the area made CE a versatile speciation tool for biomedical studies of nanomaterials containing metals.     

一步法制备含W介孔碳材料及其氧化脱硫性能研究

以钨酸钠为钨源,以乙二胺四乙酸二钠为碳源经过高温煅烧制备了含W的介孔碳材料,采用XRD、SEM、FT-IR、BET对含钨的介孔碳材料进行表征。结果表明,煅烧后介孔碳材料的表面形成了粒状含有结晶水的氧化钨(WO_3·H_2O)。相比于纯的介孔碳材料,含钨介孔碳材料的总比表面积减小。以含W介孔碳材料为催化剂,H_2O_2作为氧化剂,1-丁基-3-甲基咪唑氟硼酸盐([BMIM][BF_4])离子液体作为萃取剂,组成萃取-催化氧化脱硫体系(ECODS)并研究其对模拟油中二苯并噻吩脱除效果。考察了氧化钨负载量、反应温度、H_2O_2加入量、催化剂用量、离子液体用量以及不同类型硫化物对二苯并噻吩脱除的影响。在最佳反应条件下,催化剂对二苯并噻吩(DBT)、4,6-二甲基二苯并噻吩(4,6-DMDBT)、苯并噻吩(BT)、噻吩(TH)和真实汽油的脱除率分别达到98.6%、65.6%、61.2%、57.8%和64.3%。催化剂回收利用五次之后脱硫率略有降低,仍高达95.2%。