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1.
C. Cruces Blanco F. Garcia Sanchez 《International journal of environmental analytical chemistry》2013,93(4):513-523
Abstract A simple kinetic-spectrophotometric method for the analysis of the organophosphate insecticide methyl parathien is presented. The method is based on the alkaline hydrolysis of the insecticide into its main metabolite p-nitrophenol. The influence of reaction variables (pH and temperature), and the effect of other pesticides, are discussed. The calibration graphs (initial rate, fixed time, fixed absorbance) were linear from 2 to 30μg/ml. The precision was calculated for the different methods applied, the relative standard deviation being 6.25% for 4μg/ml. The proposed kinetic method can be applied directly to synthetic mixtures, commercial formulations and different aqueous environment, with recoveries close to 100%. 相似文献
2.
Russell G. Baughman Gabriel B. Hall 《Acta Crystallographica. Section C, Structural Chemistry》2014,70(10):975-977
Structural studies performed in this laboratory of organophosphorus pesticides continue with these related compounds. The –NO2 groups of methyl parathion (systematic name: dimethyl 4‐nitrophenyl phosphorothioate, C8H10NO5PS) and dicapthon (systematic name: 2‐chloro‐4‐nitrophenyl dimethyl phosphorothioate, C8H9ClNO5PS) make dihedral angles of 10.67 (8) and 5.8 (1)°, respectively, with the planes of their attached rings, which accompanies angular distortion at the ring C atoms to which the –NO2 groups are attached. Similar distortions are observed at the C atom to which the thiophosphate groups are attached. Significant differences in distances and angles around the phenolic O, versus the –OMe groups, explain why it is the site of hydrolysis for these compounds. A comparison of a torsion angle involving the thiophosphate group and phenolic O atom with similar pesticide structures is given and indicates steric influences on that angle. 相似文献
3.
表面增强拉曼散射(surface-enhanced Raman scattering,简称为SERS)能够提供有机分子的指纹特征信息,且具有灵敏度高和响应时间快等优点,是一项具有发展前景的分析技术。纳米结构SERS基底是获得SERS信号的关键。本文利用简便的电沉积方法在硅片上制备大面积的金微/纳颗粒阵列。金纳米颗粒之间存在大量狭小的纳米间隙,在光激发下产生大量的SERS"热点",从而具有很高的SERS灵敏度。而且,这种金微/纳结构具有高结构稳定性和化学稳定性。该结构对浓度低至10-12 M的罗丹明6G(R6G)具有很高的SERS灵敏性,且具有很好的SERS信号均匀性。利用这种微/纳结构阵列SERS基底,实现对水中低浓度农药甲基对硫磷的成功检测。这表明我们制备的金微/纳颗粒阵列在检测环境中的毒性有机物污染物方面具有潜在的应用前景。 相似文献
4.
In this paper, a new electrochemical sensor, based on modified silver nanoparticles, was fabricated using one-step electrodeposition approach. The para-sulfonatocalix[6]arene-modified silver nanoparticles coated on glassy carbon electrode (pSC6-Ag NPs/GCE) was characterized by attenuated total reflection IR spectroscopy (ATR-IR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM), etc. The pSC6 as the host are highly efficient to capture organophosphates (OPs), which dramatically facilitates the enrichment of nitroaromatic OPs onto the electrochemical sensor surface. The combination of the host-guest supramolecular structure and the excellent electrochemical catalytic activities of the pSC6-Ag NPs/GCE provides a fast, simple, and sensitive electrochemical method for detecting nitroaromatic OPs. In this work, methyl parathion (MP) was used as a nitroaromatic OP model for testing the proposed sensor. In comparison with Ag NPs-modified electrode, the cathodic peak current of MP was amplified significantly. Differential pulse voltammetry was used for the simultaneous determination of MP. Under optimum conditions, the current increased linearly with the increasing concentration of MP in the range of 0.01-80 μM, with a detection limit of 4.0 nM (S/N = 3). The fabrication reproducibility and stability of the sensor is better than that of enzyme-based electrodes. The possible underlying mechanism is discussed. 相似文献
5.
Yunrui Huang Qingxiang Zhou Junping Xiao Guohong Xie 《Journal of separation science》2010,33(14):2184-2190
This article described a new method for the sensitive determination of organophosphorus pesticides in water samples using SPE in combination with GC‐flame photometric detection. In the procedure of method development, TiO2 nanotubes were used as SPE adsorbents for the enrichment of organophosphorus pesticides from water samples. Several factors, such as eluent and its volume, sample pH, sample volume, sample flow rate, and concentration of humic acid, were optimized. Under the optimal conditions, the proposed method had good linear ranges as 0.1–40 μg/L for each of them, LOD of 0.11, 0.014, and 0.0025 μg/L, and LOQs of 0.37, 0.047, and 0.0083 μg/L for chlorpyrifos, phorate, and methyl parathion, respectively. The proposed method was validated with real environmental water samples and the spiked recoveries were over the range of 86.5–115.1%. All these results indicated that TiO2 nanotubes, as a new SPE adsorbent, would be used widespread for the preconcentraiton and determination of environmental pollutants in the future. 相似文献
6.
Anxun Zheng Chang Shen Prof. Qian Tang Dr. Cheng-Bin Gong Dr. Cheuk-Fai Chow 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(41):9643-9649
Herein, a catalytic chemosensing assay (CCA), based on a bimetallic complex, [RuII(bpy)2(CN)2]2(CuII)2 (bpy=2,2′-bipyridine), is described. This complex integrates a task-specific catalyst (CuI-catalyst) and a signaling unit ([RuII(bpy)2(CN)2]) to specifically hydrolyze methyl parathion, a highly toxic organophosphate (OP) pesticide. The bimetallic complex catalyzed the hydrolysis of the phosphate ester to generate o,o-dimethyl thiophosphate (DTP) anion and 4-nitrophenolate. Intrinsically, 4-nitrophenolate absorbed UV/Vis light at λmax=400 nm, creating the first level of the chemosensing signal. DTP interacted with the original complex to displace the chromophore, [RuII(bpy)2(CN)2], which was monitored by spectrofluorometry; this was classified as the second level of chemosensing signal. By integrating both spectroscopic and spectrofluorometric signals with a simple AND logic gate, only methyl parathion was able to provide a positive response. Other aromatic and aliphatic OP pesticides (diazinon, fenthion, meviphos, terbufos, and phosalone) and 4-nitrophenyl acetate provided negative responses. Furthermore, owing to the metal-catalyzed hydrolysis of methyl parathion, the CCA system led to the detoxification of the pesticide. The CCA system also demonstrated its catalytic chemosensing properties in the detection of methyl parathion in real samples, including tap water, river water, and underground water. 相似文献
7.
This paper describes the development and evaluation of a sequential injection method to automate the determination of methyl parathion by square wave adsorptive cathodic stripping voltammetry exploiting the concept of monosegmented flow analysis to perform in-line sample conditioning and standard addition. Accumulation and stripping steps are made in the sample medium conditioned with 40 mmol L−1 Britton-Robinson buffer (pH 10) in 0.25 mol L−1 NaNO3. The homogenized mixture is injected at a flow rate of 10 μL s−1 toward the flow cell, which is adapted to the capillary of a hanging drop mercury electrode. After a suitable deposition time, the flow is stopped and the potential is scanned from −0.3 to −1.0 V versus Ag/AgCl at frequency of 250 Hz and pulse height of 25 mV. The linear dynamic range is observed for methyl parathion concentrations between 0.010 and 0.50 mg L−1, with detection and quantification limits of 2 and 7 μg L−1, respectively. The sampling throughput is 25 h−1 if the in line standard addition and sample conditioning protocols are followed, but this frequency can be increased up to 61 h−1 if the sample is conditioned off-line and quantified using an external calibration curve. The method was applied for determination of methyl parathion in spiked water samples and the accuracy was evaluated either by comparison to high performance liquid chromatography with UV detection, or by the recovery percentages. Although no evidences of statistically significant differences were observed between the expected and obtained concentrations, because of the susceptibility of the method to interference by other pesticides (e.g., parathion, dichlorvos) and natural organic matter (e.g., fulvic and humic acids), isolation of the analyte may be required when more complex sample matrices are encountered. 相似文献
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9.
A method for preparing homogeneous protein-imprinted polymer films with orientated immobilization of template is described. The template methyl parathion hydrolase (MPH) was modified with a peptide linker (Gly-Ser)5–Cys and was immobilized on a cover glass with a fixed orientation via the linker. The activity of the fusion enzyme (MPH-L) was evaluated by determining the product's absorbance at 405 nm (A405). Both the free and the immobilized MPH-L showed higher retention of the bioactivity than the wide type enzyme (MPH-W) as revealed by the A405 values for MPH-Lfree/MPH-Wfree (1.159/1.111) and for MPH-Limmobilized/MPH-Wimmobilized (0.348/0.118). The immobilized MPH-L also formed a more homogeneous template stamp compared to the immobilized MPH-W. The molecularly imprinted polymer films prepared with the immobilized MPH-L exhibited high homogeneity with low Std. Deviations of 80 and 200 from the CL intensity mean volumes which were observed for batch-prepared films and an individual film, respectively. MPH-L-imprinted polymer film also had a larger template binding capacity indicated by higher CL intensity mean volume of 3900 INT over 2500 INT for MPH-W-imprinted films. The imprinted film prepared with the orientated immobilization of template showed an imprinting factor of 1.7, while the controls did not show an imprinting effect. 相似文献
10.
用青岛曹家汶河口沉积物中分离出的细菌L-10(希瓦氏菌属)进行了水体中甲基对硫磷的细菌降解研究.研究表明,该菌对甲基对硫磷具有显著的降解性.采用高效液相色谱/飞行时间质谱(HPLC-TOF-MS)联用技术对甲基对硫磷及其细菌降解产物进行了分析.样品经SPE-C18小柱富集分离后,进行液相色谱和在线电喷雾飞行时间质谱分析.采用C18反相色谱柱(15 cm×4.6 mm i.d. 5 μm), 线性梯度为0 min 乙腈/水(30/70),5 min 乙腈/水(30/70),20 min 乙腈/水(80/20),25 min 乙腈/水(80/20);流速0.8 ml/min,甲酸铵缓冲溶液浓度为0.1% (V/V);电喷雾正离子(ESI)模式,m/z扫描范围50~1000进行TOF-MS扫描、测定,测定结果用Analyst QS软件进行分析.结果表明,与甲基对硫磷光降解产生甲基对氧磷和对硝基酚不同,在降解菌L-10的存在下,甲基对硫磷发生了取代、氧化、还原等一系列反应,产生了相应的降解产物.降解过程的机理很复杂,从甲基对硫磷及其降解产物的分子结构式来分析,推断可能与细菌本身的代谢有关. 相似文献