A validated and fast procedure for FTIR determination of Cypermethrin and Chlorpyrifos

A FTIR methodology has been developed for the simultaneous determination of Cypermethrin and Chlorpyrifos in pesticide commercially available formulations. The method involves the extraction of both active principles with CHCl₃ and direct measurement of the peak area values between 1747 and 1737 cm⁻¹ corrected with a baseline defined at 2000 cm⁻¹ for Cypermethrin and peak height values established at 1549 cm⁻¹ corrected using a baseline situated at 1650 cm⁻¹ for Chlorpyrifos.The limits of detection achieved were of the order of 0.7 and 0.4% (w/w), and the relative standard deviation 0.4 and 0.2% for Cypermethrin and Chlorpyrifos, respectively. The developed procedure provided statistically comparable results with those obtained by HPLC, for a series of commercial samples, which validated the FTIR method. The procedure developed reduces organic solvent consumption, per sample preparation, from 51 ml CH₃CN required for HPLC to 2.5 ml CHCl₃, and reduces waste generation also increasing the sample measurement frequency, from 3 to 30 samples/h, as compared with the HPLC-UV reference method.     

毛细管气相色谱法分析水及食油样品中倍硫磷的残留量

本文提出了分别以ＣＨ２Ｃｌ，及ＣＨ３ＣＮ为水样及食油样中残留倍硫磷的萃取剂，由弗罗里硅土柱预净化，采用高分离效能的宽口径毛细管柱和高灵敏的氮磷检测器分析倍硫磷残留量的方法。该方法的灵敏度、准克度及精密度均令人满意，经实际样品测定，表明方法是可行的。     

牛血清白蛋白与十二烷基硫酸钠作用的机理

利用电动势法得到了牛血清白蛋白(BSA)与十二烷基硫酸钠(SDS)相互作用的结合等温线. 通过四阶导数紫外光谱法和荧光光谱法研究了相互作用过程中芳香族氨基酸残基微环境极性的变化. 通过研究发现, 随着SDS浓度的逐渐增大, SDS在BSA上的平均结合数(v)逐渐增大, 色氨酸(Trp)残基所处微环境的极性在减弱后保持基本不变, 酪氨酸残基所处微环境的极性在明显增强后稍有减弱, 苯丙氨酸残基所处微环境的极性略有增强. 结果表明, 当v由0增大到14时, SDS主要结合在BSA的Trp-213附近并逐渐形成聚集体, 从而诱导BSA由结构域ⅡA 开始逐渐展开. 此后, SDS呈正协同作用的特点与BSA 结合, v急剧增大. 当v约为302 时, SDS在BSA上的结合基本达到饱和, BSA的构象趋于稳定.     

重油催化裂化汽油中含硫化合物的分析

 采用气相法 ,分别利用火焰光度检测器 (FPD)和原子发射检测器 (AED)对中国石化北京燕山石油化工公司 (简称燕化 )炼油厂和石家庄炼油厂生产的重油催化裂化 (RFCC)汽油中的硫化物进行了分析。燕化炼油厂RFCC汽油中总硫只有 2 9 5mg/L ,采用FPD无法检测 ;石家庄炼油厂的RFCC汽油中总硫为 72 0 1mg/L。用标样和气相 质谱法 (GC MS)定性 ,FPD分离检测出 19种硫化物 ,主要是硫醇、噻吩类硫化物 ,硫醚类硫化物和二硫化物均未检出。用AED鉴定出燕化炼油厂RFCC汽油中的硫化物 12种 ,主要是噻吩和四氢噻吩类、低碳硫醇和二硫化物。     

Monitoring water-polluting pesticides in Hungary

A 5-year survey of pesticide active ingredients and residues in Hungarian surface water samples was carried out within the framework of a national monitoring program. Based on physicochemical and ecotoxicological properties of currently registered pesticide active ingredients, a range of analytes was selected to cover compounds that potentially contaminate surface waters due to their solubility properties or mode of use. Target analytes thus included acetochlor, atrazine, carbofuran, diazinon, fenoxycarb, metribuzin, phorate, prometryn, terbutryn, and trifluralin. During the sampling campaign these pesticides were monitored in Hungarian surface waters including streams, rivers and lakes. Samples were obtained annually in two runs: before and after pesticide sprayings in spring and early summer. Samples were prepared for analysis by solid-phase extraction and solid-phase microextraction. Target analytes were monitored by gas chromatography - mass spectrometry, using electron impact and chemical ionization techniques. Spatial distribution monitoring of the surface water pollutants indicated two heavily contaminated point sources, as well as a wide range of non-point contamination. One or more pesticide active ingredients above the detection limit of the instrumental method used were measured in 209 samples, giving the result that 59% of the samples collected during the sampling campaign contained pesticide residues.     

牛血清白蛋白与十二烷基硫酸钠作用的机理

利用电动势法得到了牛血清白蛋白(BSA)与十二烷基硫酸钠(SDS)相互作用的结合等温线. 通过四阶导数紫外光谱法和荧光光谱法研究了相互作用过程中芳香族氨基酸残基微环境极性的变化. 通过研究发现, 随着SDS浓度的逐渐增大, SDS在BSA上的平均结合数(v)逐渐增大, 色氨酸(Trp)残基所处微环境的极性在减弱后保持基本不变, 酪氨酸残基所处微环境的极性在明显增强后稍有减弱, 苯丙氨酸残基所处微环境的极性略有增强. 结果表明, 当v由0增大到14时, SDS主要结合在BSA的Trp-213附近并逐渐形成聚集体, 从而诱导BSA由结构域ⅡA 开始逐渐展开. 此后, SDS呈正协同作用的特点与BSA 结合, v急剧增大. 当v约为302 时, SDS在BSA上的结合基本达到饱和, BSA的构象趋于稳定.     

钌离子催化氧化法研究大港减压渣油组分化学结构

利用钌离子催化氧化方法对大港减压渣油芳香分、胶质和庚烷沥青质进行了选择性降解，通过GC、GC-MS等分析手段对降解反应产物中一元正构脂肪酸、α,ω-二元正构脂肪酸和苯二～六元羧酸的含量和分布分别进行了定量分析。结果表明，芳香分、胶质和庚烷沥青质中的芳香结构上都存在大量烷基取代基和桥接不同芳碳的聚亚甲基桥。烷基取代基碳数最大约为33，聚亚甲基桥最大碳数约为24，而且这两种结构单元的含量均随碳数的增加而减少，并呈现出了偶碳优势。庚烷沥青质C12以下侧链相对较多而C16＋较少，与芳香分的分布相反；正构烷基侧链的浓度按庚烷沥青质、胶质和芳香分的顺序递减。降解产物中都检测到了苯二甲酸到苯六甲酸等一系列的苯多酸，表明三个组分中都存在稠环芳香结构。庚烷沥青质中缩合程度较高的迫位缩合结构含量最高，芳香分渺位缩合结构最多，胶质介于两者之间。     

Identification of polycyclic aromatic hydrocarbons and methoxylated phenols in wood smoke emitted during production of charcoal

Summary A method for detection, quantification, and confirmation of 30 multi-class pesticide residues in fresh vegetables by gas chromatography-tandem mass spectrometry (GC-MS-MS) has been developed. The optimum ionization mode, electron impact (El-MS-MS) or chemical ionization (Cl-MS-MS), was used for different groups of pesticides in a single run. The residues were previously extracted from vegetables with dichloromethane. A 10μL aliquot of the extract can be injected in routine analysis without a clean up step when the glass liner is used with Carbofrit. Recovery efficiencies ranged 70–119% at the two different fortification levels studied and the relative standard deviation was <16.9% for all compounds. The limit of detection of each compound was 30 ng Kg⁻¹−6 μg Kg⁻¹. The proposed method was applied to the routine analysis of pesticides in vegetables grown in an important greenhouses area located in El Ejido (Almería, Spain).     

Cooperativity of conventional and unconventional hydrogen bonds involving imidazole

Correlated ab initio calculations are used to investigate the cooperativity of H‐bonds between imidazole and a pair of water molecules. H‐bonds comprise not only the conventional NH … O and OH … N types, but also CH … O and OH … φ (wherein a proton is donated to the delocalized π cloud lying above the aromatic ring). Conventional and OH … φ H‐bonds obey the normal principles of cooperativity, wherein these bonds are strengthened when a central molecule serves simultaneously as both proton donor and acceptor. In contrast, CH … O bonds do not appear to be amenable to such positive cooperativity. When placed in a polarizable medium, all H‐bonds weaken as the dielectric constant of the solvent grows. The qualitative aspects of the cooperativity are not affected by the medium, although some weakening is observed. Calculations also consider the effects of cooperativity on other aspects of the complexes, including the intermolecular distance, the effect on the covalent X‐H bond length, and IR and NMR spectral data. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006     

Fe/炭黑、Ni/炭黑催化剂对渣油加氢反应的影响

使用模型化合物在微型反应釜中研究了载体炭黑对渣油内部氢转移反应的影响。结果表明，炭黑可以明显地促进四氢萘到蒽的氢转移反应。使用等体积浸渍法制备了Fe/炭黑、Ni/炭黑催化剂并对Fe/炭黑催化剂进行了XRD、SEM表征，结果表明，金属硫化物附着在炭黑颗粒的表面，直径为1μm左右。在高压反应釜中研究了载体炭黑和以炭黑为载体的催化剂对克拉玛依常压渣油430℃加氢反应的影响，并于传统的水溶性分散型催化剂的抑焦性能进行了对比。 结果表明，Fe/炭黑、Ni/炭黑催化剂可以明显地抑制渣油加氢反应的生焦，水洗后的催化剂效果比未经水洗的催化剂抑制生焦的效果好；Ni/炭黑催化剂抑焦效果比Fe/炭黑催化剂好；Fe/炭黑催化剂比同等浓度的水溶性Fe催化剂抑焦效果好。对反应产物馏分的分析表明，Fe/炭黑催化剂可以有效地抑制渣油缩合生焦，同时在一定程度上抑制裂化反应。