Theoretical studies on the carcinogenicity of polycyclic aromatic hydrocarbons

The distinct molecular regions of a set of 28 polycyclic aromatic hydrocarbons (PAHs) showing varying degrees of carcinogenic activity (CA) have been analyzed on the basis of their calculated molecular electrostatic potential (MESP) at B3LYP/6-31+G(d,p) level of theory. The MESP, being a property directly related to electron density, clearly distinguishes the electron dense centers in the molecule into K, L, M, and newly defined N regions. Further, a quantitative structure activity relationship (QSAR) model of carcinogenicity is developed using the volume of MESP lobes at the named regions for a set of 17 carcinogenic molecules with experimentally known CA index. The QSAR equation suggested that all the geometrical regions are significant in determining the carcinogenic property of PAHs. The model clearly showed that K and M regions have activating carcinogenic effect whereas L and N regions have deactivating carcinogenic effect. The CA showed considerable enhancement when any three distinct regions are present in a PAH. On the other hand, all the PAH systems with only one type of region are inactive irrespective of whether the region is activating or deactivating. Similarly, molecules showing the presence of two types of regions are either inactive or weakly active. The essential features of both the "K, L region" and the "bay region" theories of carcinogenesis are well evident in the new QSAR model, as the former theory works on the basis of activating K and deactivating L regions whereas the latter theory is related with the activating M region.     

Explanation of the mechanism of carcinogenesis and syntheses of anticancer agents with high selectivity

Historically,leading anticancer agents have all been discovered by fortuitous events,and advances in the new anticancer agent proceed from random screening of a large quantity of the leading anticancer drug con-geners and individual and specific natural p…     

Surface water preparation procedure for chromatographic determination of polycyclic aromatic hydrocarbons and polychlorinated biphenyls

A new sample preparation procedure for the analysis of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) in water containing suspended particulate matter (SPM) has been developed. A specially designed filtration vessel coupled directly to an SPE cartridge was used for this purpose. SPM separation and analyte isolation/concentration were carried out in a single step. Both the SPE cartridge and the suspended matter collected on the filter were solvent extracted, and analyte recoveries were determined. Analyte recoveries from the filtrate ranged from 64 to 100% of the spiked amount for PAHs with the highest aqueous solubilities, and did not exceed 20% for those with the lowest solubilities. Total recoveries of PAHs from surface water containing 21 mg l(-1) SPM ranged from 65 to 121%. PCB recoveries from the particulate matter reached over 10% of the spiked amount, while those from the filtrate ranged from 20 to 57%. Total PCBs recoveries ranged from 34 to 69%.     

QUANTITATIVE EXPLANATION ON STRUCTURE-CARCINOGENIC ACTIVITY RELATIONSHIP OF AROMATIC AMINES BY DI-REGION THEORY

Di-region theory, the theory for the mechanism of carcinogenesis, has been extendedsuccessfully on the quantitative Structure-carcinogenic activity relationship (QSCAR) of 63aromatic amines. A quantitative equation for the QSCAR of aromatic amines has been estab-lished by the mechanism conception of the specialized di- functional alkylation between thenitrenium ion of the amino group and the epoxide of the aromatic ring. The agreementbetween calculation and experiment comes up to 98%. Thus, it can now express the puzzlingvariation of the carcinogenicity of aromatic amines, as a comprehensible structure-chemicalreactivity relationship.     

Quantitative explanation on structure-carcinogenic activity relationship of aromatic amines by di-region theory

Di-region theory, the theory for the mechanism of carcinogenesis, has been extended successfully on the quantitative structure-carcinogenic activity relationship (QSCAR) of 63 aromatic amines. A quantitative equation for the QSCAR of aromatic amines has been established by the mechanism conception of the specialized di-functional alkylation between the nitrenium ion of the amino group and the epoxide of the aromatic ring. The agreement between calculation and experiment comes up to 98%. Thus, it can now express the puzzling variation of the carcinogenicity of aromatic amines, as a comprehensible structure-chemical reactivity relationship.     

多环芳烃分子结构的距边矢量表征及其气相色谱保留指数预测

 从分子图论拓扑学角度出发 ,提出用六元素组成的分子距边矢量VMDE表达上百个多环芳烃化学结构 ,对 10 0种多环芳烃的毛细管气相色谱保留值进行定量相关性研究 ,发现存在良好的线性相关关系 :IR=a +bVMDE,n =10 0 ,r =0 .988,其中a ,b为回归系数 ,可用于多环芳烃的色谱保留指数的分子建模与定量预测。     

Comparison of immunoassay and gas chromatography-mass spectrometry for measurement of polycyclic aromatic hydrocarbons in contaminated soil

Polycyclic aromatic hydrocarbons (PAHs) are frequently encountered in the environment and may pose health concerns due to their carcinogenicity. A commercial enzyme-linked immunosorbent assay (ELISA), was evaluated as a screening method for monitoring PAHs at contaminated sites. The ELISA was a carcinogenic PAH (C-PAH) RaPID assay testing kit that cross-reacts with several PAHs and utilizes benzo[a]pyrene (BaP) as a calibrator. Soil samples were extracted with 50% acetone in dichloromethane (DCM) for analysis by ELISA and gas chromatography-mass spectrometry (GC-MS). The overall method precision was within ±30% for ELISA and within ±20% for GC-MS. Recovery data for spiked soils ranged from 46 to 140% for BaP as determined by ELISA. Recoveries data of the GC-MS surrogate standards, 2-fluorobiphenyl and chrysene, were greater than 70%. The GC-MS procedure detected a total of 19 priority PAHs (2-6-ring PAHs) including seven probable human carcinogens (4-6-ring B2-PAHs). The ELISA results were compared to GC-MS summation results for the total 19 target PAHs as well as for the subset of the seven B2-PAH compounds. For all soil samples, the PAH concentrations derived from ELISA were greater than the sum of B2-PAH concentrations obtained by GC-MS. ELISA determinations were also frequently greater than the results obtained by GC-MS for the total 19 PAH compounds. This discrepancy can be expected, since the ELISA is a screening assay for the detection of several related PAHs while the GC-MS procedure detects priority PAH compounds. Thus, only a subset of PAHs (e.g. 19 PAHs) in the soil samples were measured by GC-MS while additional PAHs, including alkylated PAHs, and PAH derivatives have been demonstrated to be cross-reactive in the C-PAH ELISA. Results of paired tests show that the PAH data from ELISA and GC-MS methods are significantly different (P<0.001), but highly correlated. The ELISA data had a strong positive relationship with the GC-MS summation data for the B2-PAHs as well as for the 19 PAHs targeted by the GC-MS method. Results indicate that the ELISA may be useful as a broad screen for monitoring PAHs in environmental samples.     

Multiwalled carbon nanotubes as adsorbents of solid-phase extraction for determination of polycyclic aromatic hydrocarbons in environmental waters coupled with high-performance liquid chromatography

Multiwalled carbon nanotubes (MWCNTs) were used as a novel kind of solid-phase extraction adsorbents in this work as well as an analytical method based on MWCNTs solid-phase extraction (SPE) combined with high-performance liquid chromatography (HPLC) was established for the determination of polycyclic aromatic hydrocarbons (PAHs), some of which belong to typical persistent organic pollutants (POPs) owing to their carcinogenicity and endocrine disrupting activity. Several conditions that probably affected the extraction efficiency including the eluent volume, sample flow rate, sample pH and the sample volume were optimized in detail. The characteristic data of analytical performance were determined to investigate the sensitivity and precision of the method, and the method was applied to the determination of PAHs in environmental water samples such as river water sample, tap water sample and wastewater sample from the constructed wetland effluent. The experimental results indicated that there were excellent linear relationship between peak area and the concentration of PAHs over the range of 0.04-100 microg L(-1), and the precisions (RSD) were 1.7-4.8% under the optimal conditions. The detection limits of proposed method for the studied PAHs were 0.005-0.058 microg L(-1) (S/N=3). The recoveries of PAHs spiked in environmental water samples ranged from 78.7 to 118.1%. It was concluded that MWCNTs packed cartridge coupled with HPLC was an excellent alternative for the routine analysis of PAHs at trace level.     

多环芳烃气相色谱保留指数预测与估算

按碳原子的键合特性对其进行分类,定义并计算了多环芳烃的分子距边矢量（VMDE）,在此基础上对94种多环芳烃的气相色谱保留指数（RI）进行定量相关性研究,发现色谱保留指数与分子距边矢量之间存在良好的线性关系,RI．a b VMDE,n=94,相关系数r=0.9946,均方根RMS＝8．15,同时,还进行了留一法交互检验结果为r=0.9928,RMS=9.35。表明了新分子距边矢量的合理性和有效性,可成功地用于多环芳烃气相色谱保留指数的估计与预测,有望在定量构效关系研究中获得广泛的运用。     

Sample preparation and analytical methods for polycyclic aromatic hydrocarbons in sediment

Polycyclic aromatic hydrocarbons (PAHs) are a large category of ubiquitous persistent environmental pollutants, some of them have strong carcinogenicity to human and animals. These pollutants can easily enter the river through multiple ways including rainfall, dry deposition and water washout, and deposit in the sediment. However, it is easy for them to re-enter the river water and pollute water sources, as well as aquatic animals and plants, bringing potential harm to human health. Therefore, it is requisite to accurately analyze the PAHs in sediment. In this review, the analytical methods of PAHs in sediment, focused on the methods of sample extraction, purification, concentration and determination, are summarized.     

Progress in the analytical research methods of polycyclic aromatic hydrocarbons (PAHs)

Abstract

Polycyclic aromatic hydrocarbons (PAHs) are one species of persistent organic pollutants (POPs) with strong carcinogenicity and teratogenicity. They can be widely found in the environment, which cause great harm to the ecological environment. In addition, they endanger human health by polluting food from the natural environment and food processing. Therefore, it is necessary to accurately detect PAHs in various sample matrices, which requires the accurate, practical and rapid detection methods. This review aims to investigate the progress of research methods for PAHs, including pretreatment methods and detection methods. A summary analysis of different methods is performed by searching the literature on numerous methods for detecting PAHs published in various journals. There are many pretreatment methods for PAHs, such as solid phase extraction (SPE), cloud point extraction (CPE) and so on. The most commonly used methods for detecting PAHs are high-performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS). Spectrophotometry, chromatography and chromatography-mass spectrometry have been used more frequently owing to their accuracy and convenience. At the same time, some immunological methods, such as immunosensormethods, enzyme-linked immunosorbent assays (ELISA), immunofluorescence, etc. are also widely used.     

反相色谱多二元溶剂的选择性调整

从统计热力学方法推导的溶质保留规律及其相关参数与分子结构之间的关系式出发,探讨了１６种多环芳烃在甲醇／水、乙腈／水、异丙醇／乙腈３种二元溶剂体系下选择性的差异,为确立复杂化合物分离的溶剂选择原则奠定了基础。     

Solubilities of palmitic and stearic fatty acids in supercritical carbon dioxide

The solubilities of two fatty acids, namely hexadecanoic acid (palmitic acid) and octadecanoic acid (stearic acid) in supercritical carbon dioxide (SCCO₂), were determined at T = (328 and 338) K from 12.8 MPa to 22.6 MPa. Three models, namely a thermodynamic model based on the Peng–Robinson equation of state with Kwak and Mansoori mixing rules, a model based on dilute solution theory proposed by Mendez-Santiago and Teja and a new reformulated Chrastil equation model, were used to correlate the solubilities. In all the models, the correlation constants are temperature independent. All the models successfully correlated the experimental results for the solubilities of hexadecanoic acid within 3%.     

An Efficient and Simple Breast Milk Sample Preparation to Detect Polycyclic Aromatic Hydrocarbons by Gas Chromatography-Mass Spectrometry

Journal of Analytical Chemistry - Polycyclic aromatic hydrocarbons (PAHs) can be extremely hazardous to human health due to their carcinogenicity and toxicity. Following mother exposure, a part of...     

The effect of temperature on the solubility of benzoic acid derivatives in water

Using a laser monitoring observation technique, solubilities of o-nitro-benzoic acid, p-hydro-benzoic acid, p-methyl-benzoic acid and m-methyl-benzoic acid in water have been measured in the temperature range 290.15–323.15 K. The experimental data are regressed with the Wilson equation and the λH equation. The experimental results show that solubilities of these compounds in the range of 10⁻⁴–10⁻⁵ mole fraction in water, increase significantly with temperature. Except for o-nitro-benzoic acid, the solubility data are described adequately with the Wilson equation. The λH equation gives good agreement with all experimental data. The results indicate that the molecular structure and interactions affect the solubilities significantly.     

Solubility of 3-Caffeoylquinic Acid in Different Solvents at 291–340 K

Using a laser monitoring observation technique the solubilities of 3-caffeoylquinic acid in pure solvents, water, methanol, ethanol, 1-propanol, 1-butanol, and two mixed solvents, methanol + water, ethanol + water have been determined at temperature range from 291–340 K. The experimental data were correlated by the modified Apelblat equation, λh equation, and ideal model. The calculated solubilities were turned out very consistent with the experimental results, and the modified Apelblat equation shows the best agreement.     

Strong correlation in acene sheets from the active-space variational two-electron reduced density matrix method: effects of symmetry and size

Polyaromatic hydrocarbons (PAHs) are a class of organic molecules with importance in several branches of science, including medicine, combustion chemistry, and materials science. The delocalized π-orbital systems in PAHs require highly accurate electronic structure methods to capture strong electron correlation. Treating correlation in PAHs has been challenging because (i) traditional wave function methods for strong correlation have not been applicable since they scale exponentially in the number of strongly correlated orbitals, and (ii) alternative methods such as the density-matrix renormalization group and variational two-electron reduced density matrix (2-RDM) methods have not been applied beyond linear acene chains. In this paper we extend the earlier results from active-space variational 2-RDM theory [Gidofalvi, G.; Mazziotti, D. A. J. Chem. Phys. 2008, 129, 134108] to the more general two-dimensional arrangement of rings--acene sheets--to study the relationship between geometry and electron correlation in PAHs. The acene-sheet calculations, if performed with conventional wave function methods, would require wave function expansions with as many as 1.5 × 10(17) configuration state functions. To measure electron correlation, we employ several RDM-based metrics: (i) natural-orbital occupation numbers, (ii) the 1-RDM von Neumann entropy, (iii) the correlation energy per carbon atom, and (iv) the squared Frobenius norm of the cumulant 2-RDM. The results confirm a trend of increasing polyradical character with increasing molecular size previously observed in linear PAHs and reveal a corresponding trend in two-dimensional (arch-shaped) PAHs. Furthermore, in PAHs of similar size they show significant variations in correlation with geometry. PAHs with the strictly linear geometry (chains) exhibit more electron correlation than PAHs with nonlinear geometries (sheets).