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91.
92.
The present work describes a headspace single-drop microextraction (HS-SDME) method in conjunction with gas chromatography
electron capture detection (GC–ECD) for the determination of an organophosphate insecticide, chlorpyrifos-ethyl (CPF), in
rat liver. Sample preparation included tissue homogenization with methanol in the presence of anhydrous sodium sulfate in
order to isolate CPF from the matrix, followed by dilution with 10 mL of 0.1 M H2SO4 and headspace microextraction to a 2-μL drop of 1-octanol. The main factors affecting extraction efficiency were optimized
[temperature 90 °C, preheating and extraction times of eight and six minutes, respectively, 2 g of (NH4)2SO4, stirring rate of 1000 rpm, 200 μL of methanolic extract]. The method allows for the separation and quantitation of residue
levels of CPF in the livers of rats exposed orally to that insecticide. Using internal standardization (with chlorpyrifos-methyl
used as an internal standard), the linearity of the method was demonstrated in the range 10–2500 ng g−1 with a correlation coefficient R > 0.996 and a satisfactory level of precision (RSD 3.85%, n = 6). Moreover, the results obtained with the new method do not differ from those obtained with the conventional residue
method used in our laboratory. The feasibility of this HS-SDME approach as an equivalent analytical method for the determination
of CPF in rat liver that possessess advantages such as low cost, low solvent consumption and high throughput was confirmed.
Figure Headspace single-drop microextraction 相似文献
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95.
Dr. Bilge Baytekin Dr. H. Tarik Baytekin Prof. Bartosz A. Grzybowski 《Angewandte Chemie (International ed. in English)》2014,53(27):6946-6950
Mechanical treatment of polymers produces surface cations and anions which, as demonstrated here for the first time, can drive chemical reactions. In particular, it is shown that such a mechanical treatment transforms nonconductive polyaniline into its conductive form. These results provide a mechanical means of patterning conductive polymers and also coating small polymer objects with conductive polyaniline films preventing accumulation of static electricity. 相似文献
96.
Back Cover: Gold(III)‐Mediated Contraction of Benzene to Cyclopentadiene: From p‐Benziporphyrin to Gold(III) True Tetraarylcarbaporphyrin (Chem. Eur. J. 5/2014) 下载免费PDF全文
97.
Baytekin B Baytekin HT Grzybowski BA 《Journal of the American Chemical Society》2012,134(17):7223-7226
Although it is known that contact-electrified polymers can drive chemical reactions, the origin of this phenomenon remains poorly understood. To date, it has been accepted that this effect is due to excess electrons developed on negatively charged surfaces and to the subsequent transfer of these electrons to the reactants in solution. The present study demonstrates that this view is incorrect and, in reality, the reactions are driven by mechanoradicals created during polymer-polymer contact. 相似文献
98.
Wang D Nap RJ Lagzi I Kowalczyk B Han S Grzybowski BA Szleifer I 《Journal of the American Chemical Society》2011,133(7):2192-2197
Dissociation of ionizable ligands immobilized on nanopaticles (NPs) depends on and can be regulated by the curvature of these particles as well as the size and the concentration of counterions. The apparent acid dissociation constant (pK(a)) of the NP-immobilized ligands lies between that of free ligands and ligands self-assembled on a flat surface. This phenomenon is explicitly rationalized by a theoretical model that accounts fully for the molecular details (size, shape, conformation, and charge distribution) of both the NPs and the counterions. 相似文献
99.
Peroxynitrite and hypochlorite are oxidants relevant in many pathological situations. We propose a simple spectrofluorometric assay to determine antioxidant capacity against hypochlorite and peroxynitrite based on protection against fluorescein bleaching. The assay can be performed on a microplate and requires minute amounts of material. Standard antioxidants show different reactivities for both oxidants. Antioxidant capacity of fruit bodies of edible mushrooms, tea, coffee and wine estimated as exemplary biological material point to considerable differences in the scavenging capacity of various biological material against hypochlorite, peroxynitrite and peroxyl radicals. 相似文献
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