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31.
Direct immersion solid-phase microextraction (DI-SPME) is an effective microsampling strategy for polar and ionic species in aqueous media. Nevertheless, the fiber coating is in direct contact with sample solution and affected by its conditions. To compensate this limitation and to improve the extraction efficiency, a magnetic fiber coating was prepared and employed for DI-SPME sampling under the enhancing effect of a magnetic field. Magnetic iron oxide core–shell silica nanoparticles were synthesized and embedded in polypyrrole using an in situ electropolymerization method along with simultaneous coating on the surface of a platinized stainless-steel fiber. It was then applied for magnetic-assisted DI-SPME (MA-DI-SPME) sampling of endogenous aldehydes in human urine. Sample solution pH, the magnetic field intensity, ionic strength and extraction time were evaluated as the important affecting variables. Limits of detection were obtained 0.01–0.1 ng mL?1; the calibration graphs were linear over the range of 0.1–10000 ng mL?1. The inter-fiber (fiber-to-fiber) reproducibility was found to be 10.7–12.5%. Matrix effect from urine samples was not observed at concentration levels of 0.2, 2, and 8 µg mL?1. The results showed that magnetic field increased the efficiency of DI-SPME method about two to four times. The developed strategy was successfully applied for the extraction and quantification of hexanal and heptanal (as the most important aldehyde biomarkers) in urine samples. 相似文献
Graphical Abstract
32.
Ali Reza Ghiasvand Sana Abdolhosseini Nahid Heidari Brett Paull 《Journal of the Iranian Chemical Society》2018,15(11):2585-2592
The unique features of nanostructured polypyrrole, conductivity enhancement effect of silver nanoparticles and high polar adsorptivity of polyethylene glycol were merged into polypyrrole/silver/polyethylene glycol (PPy/Ag/PEG) nanocomposite. It was synthesized and simultaneously coated on the surface of a stainless-steel fiber using an amended electropolymerization procedure. Before coating, the fiber substrate was made porous and sticky by allocating platinum dots on the surface of the stainless-steel fiber using the electrophoretic method. The prepared fiber was applied for the extraction of carvacrol and thymol (the most important antioxidants in medicinal plants) through an electroenhanced direct-immersion solid-phase microextraction (EE-DI-SPME) sampling strategy, followed by GC-FID quantification. To achieve the best efficiency, the effectual experimental variables including pH of sample solution, applied voltage, extraction temperature and time, stirring rate, and ionic strength were investigated. Under the optimal experimental conditions, the calibration curves were linear over the range of 0.5–30 µg mL?1 for thymol and 0.01–30 µg mL?1 for carvacrol. The detection limits (3Sb) and relative standard deviation (RSD%, n?=?6) were obtained to be 0.15, 0.003 µg mL?1 and 10.2, 8.7% for thymol and carvacrol, respectively. The results demonstrated the priority of the proposed fiber compared with polypyrrole and polyacrylate fibers, in terms of extraction efficiency, durability and stability. The developed method was successfully employed for the analysis of thymol and carvacrol in medicinal plants. 相似文献
33.
Nahid?TavakkoliEmail author Nasrin?Soltani Faezeh?Shahdost-fard Mahbobeh?Ramezani Hossein?Salavati Mohammad?Reza?Jalali 《Mikrochimica acta》2018,185(10):479
A highly selective electrochemical sensor was fabricated based on a modified carbon paste electrode with zinc ferrite nanoparticles (ZnFe2O4 NPs). The nanocomposite has attractive properties such as high surface-to-volume ratio and good electrocatalytic activity towards the drugs acetaminophen (AC), epinephrine (EP), and melatonin (MT), best at working voltages of 0.35, 0.09 and 0.55 V (vs. Ag/AgCl), respectively. The linear ranges (and detection limits) are 6.5–135 (0.4) μmol L?1 for AC, 5–100 (0.7) μmol L?1 for EP, and 6.5–145 (3) μmol L?1 for MT. 相似文献
34.
Ali Reza Kazemizadeh Nahid Shajari Reza Shapouri Neda Adibpour Reza Teimuri‐Mofrad Parisa Dinmohammadi 《应用有机金属化学》2016,30(3):148-153
A four‐component reaction between aromatic carboxylic acids, (N‐isocyanimino)triphenylphosphorane, ferrocenecarbaldehyde and dibenzylamine is reported. This approach is an efficient, simple and high‐yield procedure for the synthesis of 1,3,4‐oxadiazole derivatives containing a ferrocene unit. The antimicrobial activities of the products were investigated against Staphylococcus aureus and Pseudomonas aeruginosa in in vitro and in vivo assays. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
35.
Davarani SS Najafi NM Ramyar S Masoumi L Shamsipur M 《Chemical & pharmaceutical bulletin》2006,54(7):959-962
Electrochemical oxidation of catechol and some 3-substituted catechols (1a--c) has been studied in the presence of 2-chloro-5,5-dimethyl-1,3-cyclohexanedione (3) in aqueous solution using cyclic voltammetry and controlled-potential coulometry. The results indicate that the quinones derived from catechols (1a--c) participate in a Michael addition reaction with 2-chloro-5,5-dimethyl-1,3-cyclohexanedione (3) with consumption of only two electrons per molecule of (1a--c) to from the corresponding benzoforans (10a--c). The electrochemical synthesis of benzofurans has been successfully performed at a carbon rod electrode and in an undivided cell with high yields and purity. 相似文献
36.
In continuation of our investigation of characteristics and thermodynamic properties of the i‐motif 5′‐d[(CCCTAA)3CCCT)] upon insertion of intercalating nucleotides into the cytosine‐rich oligonucleotide, this article evaluates the stabilities of i‐motif oligonucleotides upon insertion of naphthalimide (1H‐benzo[de]isoquinoline‐1,3(2H)‐dione) as the intercalating nucleic acid. The stabilities of i‐motif structures with inserted naphthalimide intercalating nucleotides were studied using UV melting temperatures (Tm) and circular dichroism spectra at different pH values and conditions (crowding and non‐crowding). This study indicated a positive effect of the naphthalimide intercalating nucleotides on the stabilities of the i‐motif structures compared to the wild‐type structure which is in contrast to a previous observation for a pyrene‐intercalating nucleotide showing a decrease in Tm values. 相似文献
37.
Nasir Iravani Jalal Albadi Somaieh Varnaseri Zahra Jaberi Nahid Karami Marzieh Khadamati 《中国化学会会志》2012,59(12):1567-1570
A simple and efficient one‐pot synthesis of alkyl 2‐(alkyl)‐4‐methyl‐2‐thioxo‐2,3‐dihydrothiazole‐5‐carboxylates from the reaction of primary alkylamines and carbon disulfide in the presence of 2‐chloro‐1,3‐dicarbonyl compounds is described. This new protocol has several advantages such as lack of necessity of the catalyst, good yields, mild conditions and short times for reaction. 相似文献
38.
39.
Ali Ramazani Nahid Shajari Amir Tofangchi Mahyari Mehdi Khoobi Yavar Ahmadi Ali Souldozi 《Phosphorus, sulfur, and silicon and the related elements》2013,188(12):2496-2502
Reactions of (N-isocyanimino)triphenylphosphorane with 1,1,1-trifluoroacetone in the presence of aromatic (or heteroaromatic) carboxylic acids (3-methylbenzoic acid, 1-naphthalenecarboxylic acid, 2-naphthalenecarboxylic acid, 2-furancarboxylic acid, and 2-thiophenecarboxylic acid) proceed smoothly at room temperature and in neutral conditions to afford sterically congested 1,1,1-trifluoro-2-(5-aryl-1,3,4-oxadiazol-2-yl)-2-propanol derivatives in high yields. The reaction proceeds smoothly and cleanly under mild conditions, and no side reactions were observed. Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file. 相似文献
40.
Mohamad Javad Tahmasebi Birgani Fatemeh Seif Nahid Chegeni Mohamad Reza Bayatiani 《Journal of Radioanalytical and Nuclear Chemistry》2012,292(3):1367-1370
In consideration the radiological properties of materials and studying the scattering processes in atomic and nuclear physics, the effective atomic and mass numbers is widely employed. These numbers have been calculated for any mixed or composite materials in interaction with high energy photons (Linac in radiation therapy). A pair equation in terms of these numbers is obtained. The first equation has been derived from the conservation of mass energy law and the second by minimizing the binding energy from the semiempirical mass formula (Myers and Swiatecki formula) that gives a relation between atomic and mass numbers for stable nuclei approximately. By these equations one can obtain the effective atomic and mass numbers for any compound or mixed materials uniquely. These numbers are calculated for some materials and compared with the other studies. 相似文献