多环芳烃水中溶解度的理论计算

建立了计算多环芳烃水中溶解度的数学表达式，用量子化学方法计算了7个多环芳烃的水中溶解度，计算结果与实验测定结果相符合．多环芳烃处于水体内体系状态能量愈高，其溶解度愈小，多环芳烃中的碳氢基团越多，溶解度越小．此时体系中的溶质呈单分子态，而不是聚集态．     

Initial stages of soot formation in thermal pyrolysis of acetylene. I. Mechanism for homogeneous pyrolysis of acetylene

A probable mechanism for the homogeneous pyrolysis of acetylene, using carbene reactions, is considered. Analysis of the energetics for the probable mechanism of the initiation reactions shows the rearrangement C₂H₂CCH₂ to be the most probable. Using the energetic barriers for simple carbene reactions and formation enthalpies for more complicated carbenes, we evaluated the activation energies for the reactions mechanism. The vibrational excitation of the products of carbene reactions is taken into account. Calculations of the acetylene conversion kinetics and yields of the main gas-phase pyrolysis products, based on the carbene molecular mechanism, show significantly better agreement with available experimental data as compared to those based on traditional radical mechanisms. The calculated time for the appearance of aromatic products is close to the measured induction times for the appearance of soot particles.     

1H NMR isotope shifts arising from the substitution of 12C by 13C: application to polycyclic aromatic hydrocarbon anions

Isotope shifts are a well-established tool for structural analysis by NMR. The substitution of a protium with a deuterium is the most widely studied of these effects. However, such studies call for specific deuteration that requires complex synthetic techniques owing to the low natural abundance of deuterium. ¹³C occurs at a higher natural abundance and couples strongly with its attached proton. We have developed and refined a method to reliably observe these much smaller shifts without needing to resort to chemical synthesis. We show that carbon induced isotope shifts reflect structural features. Copyright © 2001 John Wiley & Sons, Ltd.     

Mass distribution for the microextraction of polycyclic aromatic hydrocarbon metabolites investigated with fluorescence spectrometry

Mass-balance data were acquired using fluorescence spectrometry for 2-naphthol and three polycyclic aromatic hydrocarbon (PAH) metabolites using liquid-liquid-liquid microextraction and liquid-liquid microextraction systems. The PAH metabolites are very important biomarkers, and there has been no previously reported mass-balance data on these compounds with microextraction systems. In addition, the effects of two solvent systems used in the preparation of donor and acceptor phases were investigated. The effects of the solvent systems on the partitioning process were compared. The mass balance results showed that significant amounts of the hydrophobic metabolites were held in the pores of the microfiber in both the three-phase and two-phase microextraction systems. Based on the mass-balance data, a new enrichment factor was defined as the concentration of the solute trapped in the pores of the fiber divided by the initial concentration of the solute in the donor phase. Because of the relatively large amount of the solute in the pores, it is envisioned that the solutes could be easily extracted from the pores, the extraction solvent concentrated, and further separated by capillary electrophoresis or characterized by solid-matrix phosphorescence, solution fluorescence, or mass spectrometry.     

Development of a highly efficient in-tube solid-phase microextraction system coupled with UHPLC-MS/MS for analyzing trace hydroxyl polycyclic aromatic hydrocarbons in biological samples

Hydroxyl polycyclic aromatic hydrocarbons are considered active mutagenic and carcinogenic substances and are found in extremely low levels (ng/g) in biological samples. As a result, their determination in urine and blood samples is challenging, and a sensitive and effective method for the analysis of trace hydroxyl polycyclic aromatic hydrocarbons in complex biological matrices is required. In this work, a novel macroporous in-tube solid-phase microextraction monolith was prepared via a thiol-yne click reaction, and a highly efficient analytical method based on in-tube solid-phase microextraction coupled with UHPLC-MS/MS was developed to determine hydroxyl polycyclic aromatic hydrocarbons with low detection limits of 0.137–11.0 ng/L in complex biological samples. Four hydroxyl polycyclic aromatic hydrocarbons, namely, 2-hydroxyanthraquinone, 1-hydroxypyrene, 1,8-dihydroxyanthraquinone, and 6-hydroxychrysene, were determined in the urine samples of smokers, non-smokers, and whole blood samples of mice. Satisfactory recoveries were achieved in the range of 83.1–113% with relative standard deviations of 3.2–9.7%. It was found that implementation of the macroporous monolith gave a highly efficient approach for enriching trace hydroxyl polycyclic aromatic hydrocarbons in biological samples.     

Liquid-liquid-liquid microextraction for the enrichment of polycyclic aromatic hydrocarbon metabolites investigated with fluorescence spectroscopy and capillary electrophoresis

The extraction and pre-concentration of phenol, 2-naphthol, and several hydroxyl polycyclic aromatic hydrocarbon (PAH) metabolites were investigated, using liquid-liquid-liquid microextraction (LLLME). The PAH metabolites are a very important class of compounds, and they have not been investigated previously by LLLME. For several of the hydroxyl PAH metabolites, the enrichment factors were small when using LLLME with an alkaline acceptor phase. Changing the acceptor phase to 1-octanol, which gave a two-phase system, improved the enrichment factors significantly for several of the hydroxyl PAH metabolites. For example, the enrichment factor was improved by a factor of 68.5 for 3-hydroxybenzo[a]pyrene. Enrichment factors were investigated as a function of time and stirring rate. At about 55 min the enrichment factor reached a maximum for the two-phase system and at approximately 75 min for the three-phase microextraction system. However, a 30 min extraction time was used for most of the experiments. Also, fluorescence spectroscopy was used to determine the enrichment factors and the mass distribution of the solute between the phases. Fluorescence spectroscopy was very effective in determining the very small concentrations of the solute in the various phases. In addition, capillary electrophoresis and LLLME were combined to demonstrate the substantial enrichment of 2-naphthol by combining these two approaches.     

Solid-phase extraction and purification for the quantification of polycyclic aromatic hydrocarbon metabolites in fish bile

An analytical protocol including solid-phase extraction and purification is described for the individual quantification of polycyclic aromatic hydrocarbon metabolites (hydroxylated PAHs) in liquid biological matrices such as plasma and bile. The method consists in an enzymatic deconjugation followed by a solid-phase extraction on a C₁₈ cartridge and by a cleanup on an NH₂ cartridge. Extracts are then submitted to a derivatization step before gas chromatography/mass spectrometry (GC/MS) analysis. The quantification of PAH metabolites is ensured by adding an internal standard, 1-hydroxypyrene deuterated, at the beginning of the protocol. Recoveries obtained for the entire protocol were for the major part of the compounds between 96 and 70%. However, recoveries were not so satisfying concerning 2-hydroxybiphenyl and especially 3-hydroxybenzo(a)pyrene, with 62 and 36% respectively. Finally, the protocol was applied to different fish bile samples and showed its good applicability to fish bile samples. The NH₂ cleanup step has been proved to be a very selective purification step, necessary to remove most of the bile pigments before GC/MS injection. Different PAH metabolites could be detected in those natural samples and their quantification allowed us to distinguish different levels of fish exposure.     

A review of techniques for the determination of polycyclic aromatic hydrocarbons in air

We provide an extensive review of the common methodologies employed in the analysis of airborne polycyclic aromatic hydrocarbons (PAHs). The review focuses on gas-chromatography-based approaches, in the light of their universal application with excellent separation, resolution, and sensitivity.We first describe collection methods for airborne PAHs in the gas and particle phases. We then evaluate the efficiency of extraction techniques employed for separating target PAHs from sampling media, using conventional solvent-based and emerging thermal-desorption approaches.We also describe commonly employed analytical methods with respect to their applicability to PAHs in gas and particle phases, collected from diverse environmental settings. As an essential part of basic quality assurance, we examine each method with special emphasis on key parameters (e.g., limit of detection and reproducibility).Finally, we address the likely directions of methodological developments, their limitations, and the future prospects for PAH analysis.     

In-tube silylation in combination with thermal desorption gas chromatography-mass spectrometry for the determination of hydroxy polycyclic aromatic hydrocarbons in water

For the determination of hydroxy polycyclic aromatic hydrocarbons (OH-PAHs), a simple and sensitive method based on the silylation of OH-PAHs using N,O-bis(trimethylsilyl)trifluoro acetamide (BSTFA) in combination with thermal desorption gas chromatography-mass spectrometry (TD-GC-MS) is described. This method was performed by way of direct silylation in a TD unit (in-tube silylation) coupled to a GC inlet. Both a good detection limit (4.1-1200 pg L⁻¹, S/N = 3) and higher precision (relative standard deviation < 4% on average) were achieved for 21 OH-PAHs studied using the full scan mode (m/z = 40-550). These good results were due to the highly efficient derivatization of the OH-PAHs, which was attributed to not only the moisture-free environment and programmable heating in the TD tube for the in-tube silylation, but also to the constant vapor generation of BSTFA using a capillary introduction method. Although recoveries of 21 OH-PAHs from the spiked 3% NaCl solution ranged between 9 and 304%, those of 11 OH-PAHs fell between 70 and 130% (R.S.D. < 11%). Thus, the present method was applied to a seawater sample collected from an industrial port, and nine OH-PAHs including 1- and 2-OH-fluorenone and 1,8- and 2,6-OH-anthraquinone were determined at concentrations of 0.49-5.8 ng L⁻¹. Along with these OH-PAHs, significant amounts of several long chain fatty acids (C₁₂, C₁₆, C₁₈, C₂₀ and C₂₂) and bisphenol A were also identified in the seawater sample using reference data in a library of mass spectra (match factor: >80%).     

Magnetic graphene oxide as adsorbent for the determination of polycyclic aromatic hydrocarbon metabolites in human urine

Detection of monohydroxy polycyclic aromatic hydrocarbons metabolites in urine is an advisable and valid method to assess human environmental exposure to polycyclic aromatic hydrocarbons. In this work, novel Fe₃O₄/graphene oxide composites were prepared and their application in the magnetic solid‐phase extraction of monohydroxy polycyclic aromatic hydrocarbons in urine was investigated by coupling with liquid chromatography and mass spectrometry. In the hybrid material, superparamagnetic Fe₃O₄ nanoparticles provide fast separation to simplify the analytical process and graphene oxide provides a large functional surface for the adsorption. The prepared magnetic nanocomposites were characterized by X‐ray diffraction, scanning electron microscopy, transmission electron microscopy, and vibrating sample magnetometry. The experimental conditions were optimized systematically. Under the optimal conditions, the recoveries of these compounds were in the range of 98.3–125.2%, the relative standard deviations ranged between 6.8 and 15.5%, and the limits of detection were in the range of 0.01–0.15 ng/mL. The simple, quick, and affordable method was successfully used in the analysis of human urinary monohydroxy polycyclic aromatic hydrocarbons in two different cities. The results indicated that the monohydroxy polycyclic aromatic hydrocarbons level in human urine can provide useful information for environmental exposure to polycyclic aromatic hydrocarbons.     

On a possible growth mechanism for polycyclic aromatic hydrocarbon di-cations: C(7)H(6)(2+) + C(2)H(2)

The mechanism of the bond-forming reaction between C(7)H(6) (2+) and C(2)H(2) to yield C(9) entities has been investigated by density functional theory calculations with close comparison with experimental data. It is shown that the reaction produces the C(9)H(6) (2+) and C(9)H(7) (2+) di-cations with geometries most probably derived from the indene skeleton. In comparison, the formation of linear structures of di-cations is much more energy-demanding and therefore appears improbable.     

Triazine‐based organic polymers@SiO2 nanospheres for sensitive solid‐phase microextraction of polycyclic aromatic hydrocarbons

Triazine‐based organic polymers@SiO₂ nanospheres were prepared and applied as an extraction coating onto stainless steel wires and the wires were filled into polyetheretherketone tube for in‐tube solid‐phase microextraction. Taking polycyclic aromatic hydrocarbons as targets, main factors affecting extraction performance of the tube were investigated through coupling to high performance liquid chromatography. Under the optimum conditions, an online analytical method for polycyclic aromatic hydrocarbons was established with large linear ranges (0.010‐20 µg/L), low limits of detection (0.003‐0.010 µg/L), high enrichment factors (533‐2954), and good repeatability (relative standard deviations <1.7% for intraday test, <5.0% for interday test). The analysis method was successfully applied to the detection of trace targets in real water samples and the relative recoveries ranged from 82.9 to 119.9%, which demonstrated the applicability of extraction tube in sample preparation.     

Solid-phase microextraction combined with gas chromatography/triple quadrupole tandem mass spectrometry for determination of nitrated polycyclic aromatic hydrocarbons in sediments

Nitro-polycyclic aromatic hydrocarbons have been detected in various environmental media. However, determination in sediment matrix is challenging due to the lack of a suitable method. In this study, a reliable method for determining 15 nitro-polycyclic aromatic hydrocarbons in sediments was developed based on accelerated solvent extraction and solid-phase microextraction coupled with gas chromatography–tandem mass spectrometry. The accelerated solvent extraction and solid-phase microextraction are sample pre-treatment techniques that have advantages, such as rapid operation and minimal sample volume. Initially, the solid-phase microextraction was optimized using five commercial fibers and from that 65 μm polydimethylsiloxane/divinylbenzene fiber was selected as the best fiber. Further, the accelerated solvent extraction conditions were optimized by Taguchi experimental design, such as extraction temperature (120℃), extraction solvent (dichloromethane), number of cycles (two), static extraction period (4 min), and rinse volume (90%). The method parameters, such as limits of quantitation, and intraday and interday accuracy and precision, were in the range of 0.067–1.57 ng/g, 75.2–115.2%, 69.9–115.4%, and 1.0–16.5%, respectively. Upon meeting all the quality criteria, the method was applied successfully to analyze real sediment samples. Therefore, our study creates a new prospect for the future application of direct immersion solid-phase microextraction in sediment analysis.     

加速溶剂萃取-磁固相萃取净化-气相色谱-质谱法测定土壤中16种多环芳烃和23种有机氯残留

建立了加速溶剂萃取(ASE)、磁固相萃取净化(MSPE)、气相色谱-质谱(GC-MS)测定土壤中多环芳烃和有机氯残留的方法。ASE萃取溶剂为丙酮-正己烷(1∶1, v/v),萃取温度为100℃,萃取压力为11.032 MPa,加热时间为5 min,静态萃取时间为5 min,循环萃取3次,冲洗体积为60%萃取池体积,氮气吹扫100 s。然后采用室温制备法自制ZIF-8/nZVI磁性材料用于净化萃取液,将净化液浓缩定容后进行GC-MS测定。多环芳烃和有机氯的线性范围为5～200μg/kg,线性相关系数(r²)均大于0.99;目标物的检出限(LOD,S/N=3)为0.04～1.21μg/kg。所建方法成功用于土壤样品中16种多环芳烃和23种有机氯的测定,在3个加标水平下得到的加标回收率为63.9%～112.1%,相对标准偏差(RSD)为0.4%～26.2%。研究结果表明,该方法具有灵敏度高、重现性好、回收率高等特点,适用于土壤中多环芳烃和有机氯残留的检测。     

超高效液相色谱-三重四极杆质谱法同时检测人尿中12种单羟基多环芳烃代谢物

建立了高效、准确的同时测定人体尿样中多种多环芳烃代谢物的方法。取10.0 mL尿液,酶解,经固相萃取净化浓缩、0.2 μm滤膜过滤后,以Acquity UPLC^®HSS T3（100 mm×2.1 mm,1.8 μm）为分析柱,甲醇和水为流动相,采用负离子电喷雾多反应监测模式检测样品中多环芳烃代谢物的含量。12种多环芳烃代谢物在0.04~20.0 μg/L范围内线性关系良好,相关系数>0.99,方法检出限为0.01~0.41 μg/L,平均回收率为80.0%~105%,批内RSD为1.21%~9.12%,批间RSD为4.43%~19.7%。应用该方法对淮河流域某区域的100份人体尿样进行了检测,多环芳烃代谢物的检出率为98%。该方法操作简单,灵敏度高,选择性好,可同时检测尿中12种羟基多环芳烃代谢物。     

Dynamic redox systems based on bis(spiroxanthene)-type donors with a polycyclic aromatic hydrocarbon: preparation, X-ray structures, and electrochromic response with fluorescence change

The long C-C bonds (1.614(2)-1.630(2) Å) in newly prepared title donors 2-6 are cleaved upon two-electron oxidation to afford the bond-dissociated dicationic dyes 2²⁺-6²⁺, whose electron affinities are stronger than the corresponding biphenyl-2,2′-diyl dications 1²⁺ due to the spatial proximity of two xanthenylium units. Not only UV-vis but also fluorescence spectra changed drastically upon electrolysis since only colorless neutral donors are fluorescent.     

Reinforced microextraction of polycyclic aromatic hydrocarbons from polluted soil samples using an in‐needle coated fiber with polypyrrole/graphene oxide nanocomposite

The surface of a stainless‐steel wire was platinized using electrophoretic deposition method to create a high‐surface‐area with porous and cohesive substrate. The platinized fiber was coated by the polypyrrole/graphene oxide nanocomposite by electropolymerization and accommodated into a stainless‐steel needle to fabricate an in‐needle coated fiber. The developed setup was coupled to gas chromatography with flame ionization detection and applied to extract and determine polycyclic aromatic hydrocarbons (naphthalene, fluorene, phenanthrene, fluoranthene, and pyrene) in complicated solid matrices, along with reinforcement of the extraction by cooling the sorbent, using liquid carbon dioxide. To obtain the best extraction efficiency, the important experimental variables including extraction temperature and time, temperature of cooled sorbent, sampling flow rate, and desorption condition were studied. Under the optimal condition, limits of detection for five studied analytes were in the range of 0.2–0.8 pg/g. Linear dynamic ranges for the calibration curves were found to be in the range of 0.001–1000 ng/g. Relative standard deviations obtained for six replicated analyses of 1 ng/g of analytes were 4.9–13.5%. The reinforced in‐needle coated fiber method was successfully applied for the analysis of polycyclic aromatic hydrocarbons in contaminated soil samples.     

基于轻质萃取剂的溶剂去乳化分散液-液微萃取-气相色谱法测定水样中多环芳烃

以密度小于水的轻质溶剂为萃取剂,建立了无需离心步骤的溶剂去乳化分散液-液微萃取-气相色谱(SD-DLLME-GC)测定水样中多环芳烃的新方法。传统分散液-液微萃取技术一般采用密度大于水的有机溶剂为萃取剂,并需要通过离心步骤促进分相。而本方法以密度比水小的轻质溶剂甲苯为萃取剂,将其与丙酮(分散剂)混合并快速注入水样,获得雾化体系;然后注入乙腈作为去乳化剂,破坏该雾化体系,无需离心,溶液立即澄清、分相;取上层有机相(甲苯)进行GC分析。考察了萃取剂、分散剂、去乳化剂的种类及其体积等因素对萃取率的影响。以40 μL甲苯为萃取剂,500 μL丙酮为分散剂,800 μL乙腈为去乳化剂,方法在20～500 μg/L范围内呈现出良好的线性(r2=0.9942～0.9999),多环芳烃的检出限(S/N=3)为0.52～5.11 μg/L。用所建立的方法平行测定5份质量浓度为40 μg/L的多环芳烃标准水样,其含量的相对标准偏差为2.2%～13.6%。本法已成功用于实际水样中多环芳烃的分析,并测得其加标回收率为80.2%～115.1%。