离子液体自聚集磁性多壁碳纳米管固相萃取环境水样中的磺胺类药物

将1-己基-3-甲基咪唑六氟磷酸([C6MIM] [PF6])离子液体自聚集于磁性多壁碳纳米管(Fe3O4@MWCNTs)表面,并将其作为磁性固相吸附剂,建立了同时测定环境水样中磺胺二甲嘧啶、磺胺对甲氧嘧啶、磺胺邻二甲氧嘧啶和磺胺二甲异噁唑4种磺胺类药物的涡旋辅助磁性固相萃取-高效液相色谱法.优化条件为:将20.0 mg [C6MIM] [PF6]包覆的Fe3 O4@MWCNTs分散于200 mL水样中,涡旋萃取15 min,磁性分离获取磁性吸附剂,3.5 mL 1.0％乙酸铵-甲醇溶液洗脱,洗脱液氮吹至干,300 μL甲醇溶解后待下一步高效液相色谱/二极管阵列检测器(HPLC-PDA)分析.4种磺胺类药物在0.375 ～ 75.0 μg/L范围内与峰面积呈良好的线性关系,其相关系数为0.9985 ～0.9996,检出限(S/N=3)为0.079 ～0.099 μg/L,3个加标浓度水平的回收率为80.60％ ～99.99％,日内、日间测定的相对标准偏差分别为1.3％ ～6.9％和1.2％～2.9％(n=3).结果表明,本方法简单方便,易于操作,适用于环境水样中痕量磺胺类药物的检测.     

Environmental effects on fibre reinforced polymeric composites: Evolving reasons and remarks on interfacial strength and stability

The interface between fibre and matrix of fibrous polymeric composites is most critical and decisive in maintaining sustainability, durability and also reliability of this potential material, but unfortunately a comprehensive conclusion is yet to meet the label of confidence for the engineering viability. Fiber reinforced polymer (FRP) composites are being accepted and also utilized as better and reliable alternative materials for repairing and/or replacing conventional materials, starting from tiny objects to mega structure in various engineering applications. The promise and potential of these materials are sometimes threatened in speedy replacement of conventional materials because of their inhomogeneities and inherent susceptibility to degradation due to moist and thermal environments. Environmental conditioning is traditionally believed to be a physical phenomenon but present literature has revealed that the interdiffusion between fiber and polymer matrix resin comprises of physical, chemical, mechanical, physico-chemical and mechano-chemical phenomena. The failure and fracture behavior at ambient conditions itself is a complex phenomenon till at present. The service conditions which are mostly hygrothermal in nature, along with a variation of applied loads make the mechanical behavior nearly unpredictable, far off from conclusions in evaluating the short term as well as long term durability and reliability of FRPs. It is essential to accurately simulate the initial and subsequent evolution process of this kind of damage phenomena, in order to explore the full potential of the mechanical properties of composite laminates. The present review has emphasized the need of complying scattered as well as limited literature on this front, and has focused on creating the urgency to highlight the importance of judicious uses of these materials with minimum safety factors with an aim to achieving lighter weight in enhancing specific properties.     

Ballistic and numerical simulation of impacting goods on conveyor belt rubber

Impact loading is an important process in the transport industry as it causes wear and failure of critical components. Conveyor belts are of particular importance as they are used in practically every industry where large quantities of goods are moved over short (<10 m) or long distances (>1 km). To investigate stress levels inside the material during impact loading, a gas gun was utilized to shoot 9 mm spherical steel balls onto the surface of a rubber conveyor belt. A high speed video recording system was employed in order to determine penetration depth and dissipated energy of the steel ball. Maximal penetration depths of up to 3.9 mm and maximal dissipated energies of up to 86.8 % were measured. Additionally, a numerical simulation using smooth particle applied mechanics was conducted and compared to the experimental results obtained with the gas gun. The calculated von Mises stresses affected the conveyor belts up to a maximum depth of 8.8 mm with at least 20 MPa. Maximum von Mises stresses were calculated to reach 60 MPa.     

Nanostructured copper‐coated solid‐phase microextraction fiber for gas chromatographic analysis of dibutyl phthalate and diethylhexyl phthalate environmental estrogens

A novel nanostructured copper‐based solid‐phase microextraction fiber was developed and applied for determining the two most common types of phthalate environmental estrogens (dibutyl phthalate and diethylhexyl phthalate) in aqueous samples, coupled to gas chromatography with flame ionization detection. The copper film was coated onto a stainless‐steel wire via an electroless plating process, which involved a surface activation process to improve the surface properties of the fiber. Several parameters affecting extraction efficiency such as extraction time, extraction temperature, ionic strength, desorption temperature, and desorption time were optimized by a factor‐by‐factor procedure to obtain the highest extraction efficiency. The as‐established method showed wide linear ranges (0.05–250 μg/L). Precision of single fiber repeatability was <7.0%, and fiber‐to‐fiber repeatability was <10%. Limits of detection were 0.01 μg/L. The proposed method exhibited better or comparable extraction performance compared with commercial and other lab‐made fibers, and excellent thermal stability and durability. The proposed method was applied successfully for the determination of model analytes in plastic soaking water.     

Magnetic mixed hemimicelles solid‐phase extraction coupled with high‐performance liquid chromatography for the extraction and rapid determination of six fluoroquinolones in environmental water samples

In this study, a mixed hemimicelle solid‐phase extraction method based on Fe₃O₄ nanoparticles coated with sodium dodecyl sulfate was applied for the preconcentration and fast isolation of six fluoroquinolones in environmental water samples before high‐performance liquid chromatography determination. The main factors affecting the extraction efficiency of the analytes, such as amount of surfactant, amount of Fe₃O₄ nanoparticles, extraction time, sample volume, sample pH, ionic strength, and desorption conditions, were investigated and optimized. The method has detection limits from 0.05 to 0.1 ng/mL and good linearity (r ≥ 09948) in the range 0.1–200 ng/mL depending on the fluoroquinolone. The enrichment factor is ～200. The recoveries (at spiked levels of 1, 5, and 50 ng/mL) are in the range of 79–120%.     

Development of a magnetic solid‐phase extraction coupled with high‐performance liquid chromatography method for the analysis of polyaromatic hydrocarbons

A novel magnetic solid phase extraction coupled with high‐performance liquid chromatography method was established to analyze polyaromatic hydrocarbons in environmental water samples. The extraction conditions, including the amount of extraction agent, extraction time, pH and the surface structure of the magnetic extraction agent, were optimized. The results showed that the amount of extraction agent and extraction time significantly influenced the extraction performance. The increase in the specific surface area, the enlargement of pore size, and the reduction of particle size could enhance the extraction performance of the magnetic microsphere. The optimized magnetic extraction agent possessed a high surface area of 1311 m²/g, a large pore size of 6–9 nm, and a small particle size of 6–9 μm. The limit of detection for phenanthrene and benzo[g,h,i]perylene in the developed analysis method was 3.2 and 10.5 ng/L, respectively. When applied to river water samples, the spiked recovery of phenanthrene and benzo[g,h,i]perylene ranged from 89.5–98.6% and 82.9–89.1%, respectively. Phenanthrene was detected over a concentration range of 89–117 ng/L in three water samples withdrawn from the midstream of the Huai River, and benzo[g,h,i]perylene was below the detection limit.     

Enantioselective comprehensive two‐dimensional gas chromatography. A route to elucidate the authenticity and origin of Rosa damascena Miller essential oils

The analysis of Bulgarian and Turkish Rosa damascena Miller essential oils was performed by flow‐modulated comprehensive two‐dimensional gas chromatography using simultaneous detection of the second column effluent by flame ionization and quadrupole mass spectrometric detection. Enantioselective separations were obtained by running the samples on 2,3‐di‐O‐ethyl‐6‐O‐tert‐butyldimethylsilyl‐β‐cyclodextrin column as the first column and on polyethylene glycol as the second column. The determination of enantiomeric or diastereomeric excess of some terpenoic solutes is a possible route for quality or authenticity control as well as for the elucidation of the country of origin.     

云南东川区域重金属环境暴露健康风险评价

以云南省昆明市东川主要河流及附近土壤、植物为研究对象,对其进行采样分析,并根据美国环境保护署(U.S.EPA)推荐健康风险评价方法对东川流域多种环境因素进行了重金属的健康风险评价。结果表明,水环境中致癌物质造成的风险最大,风险值在2.35×10^(-4)~8.27×10^(-4),达到U.S.EPA推荐的最大值10^(-4),植物根部的健康风险值为0.40×10^(-1)~7.00×10^(-1),茎叶部分的风险值为2.42×10^(-2)~15.24×10^(-2),根部存在的重金属对人体的健康风险约为茎叶部分的5倍;土壤中非致癌物质的健康风险影响较大,总健康风险值区间为0.64×10^(-1)~3.83×10^(-1)。评价结果可为该区域地表水、土壤和植物资源的污染治理、保护开发提供依据。     

The electrochemical evaluation of antipsychotic drug (promethazine) in biological and environmental samples through samarium cobalt oxide nanoparticles

In this work, we developed a perovskite structured samarium cobalt oxide nanoparticles (SmCoO₃ NPs) with the aid of the co-precipitation method. The rare earth metal (Sm) and cobalt oxide combined to form a perovskite lattice structure. One-pot route synthesized SmCoO₃ NPs were scrutinized successfully through various physicochemical techniques. Concerning its effective thermal stability and electrical properties, the synthesized SmCoO₃ NPs have been effectively implemented in the electrochemical evaluation of promethazine hydrochloride (PHY) using cyclic voltammetry. The electrochemical detection of PHY was performed through SmCoO₃ NPs-modified glassy carbon electrode (GCE) and unmodified GCE. The electron transfer kinetics, effect of scan rate, the influence of pH, electroactive surface area, selectivity, and sensitivity have been studied. The electron charge transfer rate (R_ct) and electrolyte resistance (R_s) were calculated to be 105.59 (Ω) and 150 (Ω) in the ferricyanide probe, indicating great facilitation of the electron transfer between PHY and SmCoO₃ NPs deposited on the electrode surface. Further, the optimized SmCoO₃-modified GCE exemplifies excellent selectivity, storage stability, reproducibility, repeatability, detection limit (5 nM), sensitivity (0.594 μA μM^?1 cm^?2), and wide consecutive linear ranges, respectively. Besides, the proposed method has been effectively employed for the detection of PHY in the various real samples which reveals good recoveries of 95.40–99.17%.