Hydrophobic Molecular Similarity from MST Fractional Contributions to the Octanol/water Partition Coefficient

Summary The use of a recently proposed hydrophobic similarity index for the alignment of molecules and the prediction of their differences in biological activity is described. The hydrophobic similarity index exploits atomic contributions to the octanol/water transfer free energy, which are evaluated by means of the fractional partitioning scheme developed within the framework of the Miertus-Scrocco-Tomasi continuum model. Those contributions are used to define global and local measures of hydrophobic similarity. The suitability of this computational strategy is examined for two series of compounds (ACAT inhibitors and 5-HT₃ receptor agonists), which are aligned to maximize the global hydrophobic similarity using a Monte Carlo-simulated protocol. Indeed, the concept of local hydrophobic similarity is used to explore structure–activity relationships in a series of COX-2 inhibitors. Inspection of the 3D distribution of hydrophobic/hydrophilic contributions in the aligned molecules is valuable to identify regions of very similar hydrophobicity, which can define pharmacophoric recognition patterns. Moreover, low similar regions permit to identify structural elements that modulate the differences in activity between molecules. Finally, the quantitative relationships found between the pharmacological activity and the hydrophobic similarity index points out that not only the global hydrophobicity, but its 3D distribution, is important to gain insight into the activity of molecules. J.M.M. and S.P. have contributed equally to this study.     

难降解有机废水的催化氧化法处理

催化氧化法可通过多种途径来加强传统的化学法处理效果，目前已成为难降解有机废水处理的一项重要新技术。本文介绍了光催化氧化法、均相氧化法、多相氧化法(包括电催化氧化法)以及超临界水氧化技术的国内外研究现状及特点，并对其在有机废水中的应用情况和发展前景作了扼要评述。     

Multi-determination of organic pollutants in water by gas chromatography coupled to triple quadrupole mass spectrometry

A multi-determination method has been developed for the determination and confirmation of 68 organic pollutants in water samples by gas chromatography coupled to triple quadrupole mass spectrometry (GC-MS/MS). The following chemical families were determined in a chromatographic run of less than 26?min: polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), polybrominated diphenylethers (PBDEs), and pesticides (organochlorine, organophosphorus, triazine and others). The sample preparation involved a liquid-liquid extraction (LLE) procedure, obtaining recoveries ranging from 70 to 130% when dichloromethane was used as the extracting solvent. The detection limits of the proposed method were between 0.75 and 19.8?ng?L^?1. Samples from the Maipo River in central Chile were taken from 29 different points. Seven pesticides and two PAHs were detected in field collected samples with concentrations ranging from 10 to 95?ngL^?1. Concentrations of benzo[a]pyrene in environmental samples ranged from 25 to 33?ngL^?1 and were near the maximum levels established by the European Union Directives (50?ng?L^?1).     

水环境介质中有机污染物微观分布的理论模型：污染物.水复合体 …

以水簇模拟水环境介质,水体中有机污染物的分子状态用水－有机污染物分子复合体模拟,得出有机污染物在水环境介质中微观分布的数学表达式,经过微观动力学方法处理,得到了相应的数学解析式。用ａｂ ｉｎｉｔｉｏ方法ＳＴＯ－３Ｇ基组计算了４个多环芳烃在水中的微观分布情况,计算结果与辛醇－水分配系数的实验值相吻合。     

Improved RP-HPLC Determination of Kow for Some Chloroaromatic Chemicals Using Molecular Connectivity Indices

Abstract

Estimated values of Kow for chlorobenzenes and chloroanilines were produced by means of RP-HPLC. The method has a good predictive capability, giving similar results to direct experimental measures like the slow stirring method (SSM), at least within the single classes of compounds. Nevertheless for a good predictive capability each class requires a separate regression equation. Better estimations of Kow were obtained by means of a biparametric equation, valid for both classes of compounds, using as independent variables RP-HPLC values and second order molecular connectivity (² X).     

Methodical approach for the use of GC-TOF MS for screening and confirmation of organic pollutants in environmental water

The potential of gas chromatography coupled to time-of-flight mass spectrometry (GC-TOF MS) for the screening of organic pollutants in water was explored. After a conventional SPE step with C(18) cartridges, the comparison of spectra with available libraries together with an evaluation of the mass accuracy was the first approach used for the screening and confirmation of target analytes. However, at low analyte concentrations (i.e. below 0.1 microg/l), this procedure was not feasible and the use of the application manager TargetLynx was evaluated. This application allows the selection of up to five representative ions per analyte, measured with high mass accuracy, and their intensity ratio evaluation. Ion selection, extraction mass window and concentration levels were found to be the critical parameters. The reference compound used as 'lock mass' was also found to affect to the quality of information obtained in some particular cases.Full spectral acquisition data generated by the TOF MS analyzer allowed investigation of the presence of several analytes in samples in a post-target style, without the need of reanalyze the water samples.Finally, a methodical approach was established for the reliable screening and confirmation of organic pollutants (PAHs, pesticides, octyl/nonyl phenols) in real-world samples, which led to satisfactory results of approximately 0.1 microg/l.     

太湖水体中有机污染物的分析

利用超临界流体萃取与热脱附两种样品预自理方法的优势互补,与气相色谱分析相结合对太湖水体中不同沸点有机污染物进行了分析,发现太湖水中除了烃类污染物外还存在大量含氮有机污染物。其分布表明入湖河道中排放的工业污染物的流入是导致太湖水富营养化的一个重要因素。     

高效液相色谱-串联质谱法同时测定水中13种有机污染物

以地表水环境质量标准严格控制的特定项目为依据,建立了直接进样-高效液相色谱-串联质谱同时测定水中13种化学性质差异较大的有机污染物的分析方法,这13种有机污染物为乐果、敌敌畏、敌百虫、对硫磷、甲基对硫磷、马拉硫磷、内吸磷、丙烯酰胺、苯胺、联苯胺、甲萘威、微囊藻毒素-LR、阿特拉津。水样经0.22 μm尼龙66滤膜过滤后,采用Kromasil 100-5 C18柱(150 mm×2.1 mm, 5 μm)分离,以甲醇-0.01%甲酸水溶液为流动相进行梯度洗脱,流速0.5 mL/min,柱温40 ℃,电喷雾正离子模式(ESI⁺)电离,多反应监测模式(MRM)进行检测,外标法定量。13种化合物的浓度与其峰面积在一定浓度范围内均呈现良好的线性关系(r≥0.9995),方法检出限为0.02~0.1 μg/L。测定低、中、高浓度的加标样品,13种化合物的相对标准偏差为0.5%~5.0%(n=6),实际样品加标平均回收率为81.2%~112%。此方法灵敏度高、干扰小、分析速度快,可适用于地表水、地下水中这13种有机污染物的同时分析。     

Sorption characteristics and mechanisms of organic contaminant to carbonaceous biosorbents in aqueous solution

A series of carbonaceous biosorbents was prepared by pyrolyzing pine needles,a model biomass,at various temperatures (100-700℃) under an oxygen-limited condition for 6h. The elemental composi-tions and the specific surface areas (BET-N2) of the biosorbents were analyzed. Sorption properties of 4-nitrotoluene to the biosorbents and their mechanisms were investigated,and then correlated with the structures of the biosorbents. The result shows that with the increase of the pyrolytic temperature,the aromaticity of the carbonaceous biosorbents increases dramatically and the polarity (the (N O)/C atomic ratio) decreases sharply. Correspondingly,conformations of the organic matter in the biosor-bents transform gradually from a "soft-state" to a "hard-state" and the specific surface areas of the resultant biosorbents extend rapidly. The sorption isotherms fit well with the Freundlich equation. The regression parameters (i.e.,N and lgKf) are linearly related to the aromaticity indices (the H/C atomic ratio). Contributions of adsorption and partition to total sorption of the carbonaceous biosorbents are quantified. The adsorption of the carbonaceous biosorbents increases quickly with the increase of the pyrolytic temperature. The saturated adsorption amounts (Qmax) increase linearly with the increase of the specific surface areas (SA) of the biosorbents. For the carbonaceous biosorbents with hard-state carbon,the calculated normalized-Qmax values by SA are comparable to the theoretical estimation (2.45 μmol/m2). In comparison,for the carbonaceous sorbents with soft-state carbon,the calculated nor-malized-Qmax values by SA are much higher than the theoretical estimation. The partition coefficients (Kom) increase with the decrease of the polarity of the biosorbents,reaching a maximum,and then de-crease sharply with further decreasing the polarity,suggesting that partition mechanism be dominated by the compatibility and accessibility of the sorbent medium with organic pollutant. These observations will provide a theoretical and practical reference to design a cost-effective and high-efficient sorbent,and to accurately predict sorption properties and mechanisms of a given sorbent.     

Current Trends in the Application of Nanomaterials for the Removal of Pollutants from Industrial Wastewater Treatment—A Review

In the recent decades, development of new and innovative technology resulted in a very high amount of effluents. Industrial wastewaters originating from various industries contribute as a major source of water pollution. The pollutants in the wastewater include organic and inorganic pollutants, heavy metals, and non-disintegrating materials. This pollutant poses a severe threat to the environment. Therefore, novel and innovative methods and technologies need to adapt for their removal. Recent years saw nanomaterials as a potential candidate for pollutants removal. Nowadays, a range of cost-effective nanomaterials are available with unique properties. In this context, nano-absorbents are excellent materials. Heavy metal contamination is widespread in underground and surface waters. Recently, various studies focused on the removal of heavy metals. The presented review article here focused on removal of contaminants originated from industrial wastewater utilizing nanomaterials.     

保留时间两点校正反相高效液相色谱法测定持久性有机污染物的正辛醇-水分配系数

采用改进的反相高效液相色谱法(RP-HPLC)测定了持久性有机污染物(POPs)包括多环芳烃(PAHs)、多氯二苯并二恶英(PCDDs)、多氯二苯并呋喃(PCDFs)和十溴二苯乙烷(DBDPE)等的正辛醇-水分配系数(logKow)。采用保留时间双点校正法(DP-RTC)校正因色谱柱老化等引起的保留时间漂移。以37种有可靠logKow实验值的苯系物、PAHs、PCDD/Fs类似物为模型化合物,建立了logKow和外推至纯水相的保留因子logkw的定量结构-色谱保留关系(QSRR)模型,回归方程为logKow=(1.18±0.02)logkw+(0.36±0.11),其相关系数(R2)为0.985,交叉验证相关系数(R2cv)为0.983,标准偏差(SD)为0.16。进而,用4个已有可靠logKow实验值的验证化合物(联苯、芴、PCDD 1和PCDF 114)对模型进行了外部验证,表明RP-HPLC测得的logKow值与摇瓶法/慢搅法结果有很好的一致性,尤其是对疏水性强的化合物。采用该模型测定了29种特别受关注的POPs的logKow值,这些化合物的logKow实验值均未见报道。所建立的DP-RTC-HPLC是测定强疏水性POPs的logKow值的一种值得推荐的方法。     

Molecular graph fingerprint: a new molecular structural characterization method for the modelling and prediction of chromatographic retention behaviour of several persistent organic pollutants

How to extract and characterize information on molecular microstructures is deemed to be the key task to accurately simulate and predict molecular properties. In terms of atomic attributes, atoms in a molecule are divided into three levels. Based upon that, inter-atomic correlations are mapped to certain reasonable spatial coordinates in virtue of radial distribution function, generating the novel molecular graph fingerprint (MoGF), which essentially provides insight into molecular inner structures. MoGF, committing itself to transformation of molecular structures into characteristic graph curves, shows valuable advantages such as easy calculation, experimental parameters-free, rich information content, and structural significance and intuitive expressions. QSRR studies were performed for 115 polychlorinated dibenzofurans (PCDFs), 41 polychlorinated dibenzo-p-dioxins (PCDDs), 62 polychlorinated naphthalenes (PCNs), and 210 polychlorinated biphenyls (PCBs including the biphenyl)) tested for their retention behaviours on gas chromatographic column DB-5. The resulting PLS models showed good performances with correlation coefficients for both training and test sets above 0.97.     

Trace enrichment of polar pollutants from water and the influence of humic substances

Summary A practical liquid chromatographic early-warning system for polar pollutants in water ought to have detection limits at a level below a microgram per litre. Using ultraviolet absorbance detection this normally necessitates trace enrichment of the samples. In this study ten different sorbents have been tested with respect to their enrichment capacity. The hydrophobic polymeric PLRP-S material, in combination with a C-18 modified analytical column, proved to be the best choice. The influence of humic substances, present in surface water, was also studied. Lowering of the sample pH, resulted in a significant increase in the interferences due to the humic substances.     

Direct analysis of bottom sediments by a microcoulometric titration method for determination of total organic halide pollutants

Up to now the content of the organic halides in sediments was measured as extractable organic halides compounds by different methods including microcoulometric titration one. We describe a procedure for microcoulometric determination of total organic halide pollutants by using a direct combustion of the sediments into the microcoulometric system furnace. An accelerated removal of the inorganic chlorides by reaction with potassium nitrate using ultrasonic radiation was attained. The procedure was validated for analysis of bottom sediments from natural and anthropogenic sources. The repeatability RSD = 8.5%, the expanded relative uncertainty U (n = 7, P = 95%, k = 2) = 6.4%, the reproducibility RSD was within the range 10.0–7.3%, the average recovery R = 97.6% and method LOD = 11 mg kg⁻¹ Cl. Correspondence: Zara V. Aneva, Analytical Department, University “Prof. Dr. Assen Zlatarov”, Nr. 1 Prof. Yakimov street, 8010 Bourgas, Bulgaria     

Modelling photochemical transformation of emerging organic pollutants in surface waters: effect of water level fluctuations following outflow or evaporation,relevant to arid and semi-arid environments

Water bodies located in arid and semi-arid environments undergo important fluctuations of the water level, and water loss in the dry season may occur through phenomena such as outflow and evaporation. Water scarcity often exacerbates the impact of pollution, because harmful compounds can reach very high concentration values in the presence of relatively low water volumes. Among self-cleansing (depollution) processes of water bodies, photochemical reactions are expected to play an important role in pollutant attenuation, although sometimes they yield harmful intermediates. In this work, the effects of water-level fluctuations on photochemical reactions were studied by means of a modelling approach. The model applies to well-mixed water bodies, such as the shallow ones that are more likely to undergo fluctuations of the water level. We investigated how water outflow and evaporation (as well as a mixed scenario) might modify the steady-state concentrations of the most important photoreactive transients (^?OH, CO₃^–?, ¹O₂ and triplet states of chromophoric dissolved organic matter, ³CDOM*). Under the same conditions, the possible phototransformation of emerging pollutants such as carbamazepine, ibuprofen, 2,4-dichloro-6-nitrophenol and 2,4-dinitrophenol was also assessed. It is shown that water loss would generally enhance photochemical reactions, but to a variable extent depending on the actual pathway. Outflow would favour all photoprocesses, and particularly those involving ^?OH and CO₃^–?. Conversely, evaporation would enhance reaction with ¹O₂ and ³CDOM* while having practically no effect on ^?OH, CO₃^–? and direct photolysis. Enhancement of photochemical self-cleansing of water bodies would partially reduce the pollution impact, but in some cases harmful compounds may be generated.     

溶剂浮选法分离富集工业废水中痕量有机污染物的研究

采用溶剂浮选法对工业废水中痕量有机污染物进行分离富集，用气相色谱-质谱(GC-MS)联用法对其进行鉴定。针对废水中几种主要有机污染物，对影响溶剂浮选的参数进行了优化。所述方法用于分析某石化工业废水中主要存在的39种痕量有机污染物，结果表明这是一种简便、可行的水质分析前处理方法。     

Analysis of persistent organic pollutants in marine sediments using a novel microwave assisted solvent extraction and liquid-phase microextraction technique

A simple and novel analytical method for quantifying persistent organic pollutants (POPs) in marine sediments has been developed using microwave assisted solvent extraction (MASE) and liquid-phase microextraction (LPME) using hollow fibre membrane (HFM). POPs studied included twelve organochlorine pesticides (OCP) and eight polychlorinated biphenyl (PCB) congeners. MASE was used for the extraction of POPs from 1 g of sediment using 10 ml of ultrapure water at 600 W for 20 min at 80 degrees C. The extract was subsequently subjected to a single step LPME-HFM cleanup and enrichment procedure. Recovery varied between 73 and 111% for OCPs; and 86-110% for PCBs, and exceeded levels achieved for conventional multi-step Soxhlet extraction coupled with solid-phase extraction. The method detection limit for each POP analyte ranged from 0.07 to 0.70 ng g(-1), and peak areas were proportional to analyte concentrations in the range of 5-500 ng g(-1). Relative standard deviations of less than 20% was obtained, based on triplicate sample analysis. The optimized technique was successfully applied to POP analysis of marine sediments collected from the northeastern and southwestern areas of Singapore's coastal environment.