关键词：
Crystal violet;High performance liquid chromatography;Immunoaffinity column;Leuco metabolites;Malachite green
摘要：
A high performance liquid chromatography method with visible detection (HPLC-VIS) for the determination of malachite green (MG), crystal violet (CV), leucomalachite green (LMG), and leucocrystal violet (LCV) in fish has been developed after clean-up through an immunoaffinity column (IAC). Residues were simultaneously extracted from fish muscle with acetonitrile and ammonium acetate buffer. The leuco-forms, LMG and LCV, were oxidized quantitatively to the chromic CV and MG by reaction with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone. Extracts were then purified on an IAC which prepared by immobilizing the anti-MG-CV antibodies by the sol-gel method. Finally, the eluents were analyzed by HPLC-VIS. The limits of detection were 0.15, 0.1, 0.18 and 0.14 ng/g for MG, CV, LMG and LCV, respectively. The average recoveries in samples fortified with MG, CV, LMG and LCV over the range 0.5-10 ng/g were from 71.6% to 96.8% with RSDs of 5.1-12.3% (n = 6). This novel method was confirmed by liquid chromatography-tandem mass spectrometry with electrospray interface in positive mode using multiple reaction monitoring. (c) 2012 Elsevier B.V. All rights reserved.
摘要：
A sensitive and selective electrochemical sensor for metronidazole (MNZ) was developed. The core–shell metronidazole-magnetic molecularly imprinted polymer (MMIP) was synthesized and then attached to the surface of magnetic glassy carbon electrode (MGCE) with the help of magnetic force in order to prepare MMIP/MGCE sensor. The performance of the obtained imprinted sensor was investigated by cyclic voltammetry and electrochemical impedance spectroscopy. Various factors, known to affect the response behavior of the MMIP/MGCE electrode, were studied and optimized. The imprinted sensor exhibits high recognition ability and affinity for MNZ in comparison with the nonimprinted one. In addition, the MMIP/MGCE also shows good stability and acceptable reproducibility for the determination of MNZ. Under the optimal experimental conditions, the current response of the electrochemical sensor was linear to MNZ concentrations in the range from 5.0 × 10−8 to 1.0 × 10−6 M, with the detection limit of 1.6 × 10−8 M. The method was successfully applied to the analysis of MNZ in milk samples and honey samples with acceptable recoveries of 93.5–102.2%.
摘要：
Rationally designed biosynthetic models provide fantastic advantages for addressing important issues in chemistry and biology. Previously, two distal histidines were introduced in the heme pocket of myoglobin (Mb) at positions 29 and 43. The resultant His29 and His43, together with the native His64, formed a metal-binding site in the designed L29H/F43H Mb mutant, which closely mimics the heterobinuclear center of native cytochrome c oxidase (CcO). Instead of studying the oxidase activity, we herein investigated the cross-reactivity, i.e., the peroxidase activity of this mutant, as well as the effect of metal ions binding to the designed metal-binding site on protein reactivity. It was found that the introduced two distal histidines with no bound metal ion serve to improve the peroxidase activity of L29H/F43H Mb compared with that of WT Mb containing a single distal histidine, whereas the binding of metal ions such as Cu(II) and Zn(II) to L29H/F43H Mb inhibits the catalytic activity to a different extent. These findings provide valuable insights into the peroxidase activity observed for the native CcO, as well as the role of metal ion in fine-tuning the protein cross-reactivity.
摘要：
This study assesses enantioselectivity on the degradation of tebuconazole in wheat grain, straw, and soil in Beijing and Zhejiang under open field conditions. After agricultural application, the analytes were extracted from soil and grain with acetonitrile, and from straw with acetonitrile containing 1% acetic acid through ultrasonic extraction. The extracts were cleaned by dispersive-solid phase extraction, and determined by chiral liquid chromatography-tandem mass spectrometry with a Lux amylose-2 column. The results of field trials indicated that the degradation of tebuconazole enantiomers followed first-order kinetics in straw and soil at the two sites. Their half-lives in straw ranged from 3.88 to 4.93 days, which were shorter than those in soil ranging from 40.76 to 43.86 days. The (-)-tebuconazole showed faster degradation in straw from Beijing and Zhejiang. In Zhejiang soil, preferential degradation of (+)-tebuconazole was observed, whereas (-)-tebuconazole was preferential in Beijing soil. The terminal residues of (-)-tebuconazole in most grains were higher than those of its antipode, indicating significant enantioselective residues.
期刊：
Journal of Radioanalytical and Nuclear Chemistry,2013年298(2):903-908 ISSN：0236-5731
通讯作者：
Wang, Yanfei
作者机构：
[Yang, Yan; Wang, Yanfei] Univ South China, Sch Chem & Chem Engn, Hengyang 421001, Peoples R China.;[Feng, Yixiao; Shi, Weiqun; Wang, Lin] Chinese Acad Sci, Inst High Energy Phys, Key Lab Nucl Analyt Tech, Beijing 100049, Peoples R China.
通讯机构：
[Wang, Yanfei] U;Univ South China, Sch Chem & Chem Engn, Hengyang 421001, Peoples R China.
关键词：
Uranium;BSA;Secondary structure;FT-IR/ATR
摘要：
Interest in bio-toxicology of uranium resulting from its radioactive heavy metal property has been growing enormously in recent years. The interactions between uranium(VI) [U(VI)] and bovine serum albumin (BSA) at physiological pH were studied by spectroscopic methods. Fuorescence results revealed the formation of BSA–U(VI) complex, the binding constants as well as the number of binding sites were determined. In particular, the effects of U(VI) binding on the secondary structures of BSA were examined by means of Fourier transformation infrared spectroscopy equipped with attenuated total reflection (FT-IR/ATR). It was found that the α-helix component of BSA decreased gradually with increasing concentration of U(VI). In contrast, the β-sheets, turns, and random coil structures all increased correspondingly. Our work would shed light on the possible interaction mechanism between U(VI) and proteins in aqueous solutions.
