Polycyclic Aromatic Hydrocarbons Formation from Fuel and Additives Combustion

A study has been made of the effect of additives to the fuel of a turbulent diffusion flame on the formation of soot and polycyclic aromatic hydrocarbons (PAHs). Fuels containing a polystyrene thickener doped with benzene proved to have many advantages over unthickened fuels. Most significant were an increase in the burning time and the flash point. Nevertheless, polystyrene and benzene additives to a considerable extent increased the formation of soot and PAHs. The analysis of PAHs in this study was made by capillary gas chromatography (GC) and capillary gas chromatography/mass spectrometry (GC/MS). A total of 42 individual compounds were characterized by their retention indices and mass spectra.     

Comparative Analysis of Polycyclic Aromatic Hydrocarbons and Halogenated Polycyclic Aromatic Hydrocarbons in Different Parts of Perilla frutescens (L.) Britt.

Perilla frutescens (L.) Britt., a medicinal herb and edible plant, is very popular among East Asian countries. The perilla leaves, stems and seeds can be used as traditional medicines and foods. Polycyclic aromatic hydrocarbons (PAHs) and halogenated PAHs (HPAHs) are organic pollutants that are widely present in the environment, such as in water, air and soil, and are harmful to humans. In this study, the contents of 16 PAHs and 4 HPAHs in perilla leaves, stems and seeds were determined by gas chromatography tandem mass spectrometry (GC-MS). A total of 12 PAHs were detected in all samples, and no HPAHs were detected. The total contents of PAHs in perilla leaves, stems and seeds varied from 41.93 to 415.60 ng/g, 7.02 to 51.52 ng/g and 15.24 to 180.00 ng/g, respectively. The statistical analyses showed that there were significant differences in the distribution of PAHs in perilla leaves, stems and seeds. On the basis of the toxic equivalent quantity (TEQ) and incremental lifetime cancer risk (ILCR) model, the cancer risks of the intake of perilla leaves, stems and seeds were assessed to be from 3.30 × 10⁻⁸ to 2.11 × 10⁻⁵, 5.52 × 10⁻⁹ to 5.50 × 10⁻⁸ and 1.20 × 10⁻⁸ to 1.41 × 10⁻⁷, respectively. These were lower than 10⁻⁴ (the priority risk level of the EPA) and suggested that there may be almost no cancer risk from the intake of these traditional Chinese medicines (TCMs).     

土壤样品中多环芳烃的GC-MS快速分析方法

多环芳烃(PAHs)是含有多个苯环并具有致毒、致癌和致突变作用的有机化合物,主要由人类的现代化活动产生,通过大气、水等的传递最终污染土壤,而严重污染的土壤会影响农业耕作,最终危害人类健康.美国环保总署确定了16种PAHs作为优先监测污染物,中国政府列出的"中国环境优先监测黑名单"中包括7种PAHs[1].     

多环芳烃的污染及防治

多环芳烃污染是有机污染中最常见的一种,也是对人体危害较大的一种。本文较为详细地阐述了多环芳烃污染的来源、对人体的危害及防治措施。     

Nitration of Polycyclic Aromatic Hydrocarbons Using a Supported Catalyst

We report the use of catalyst, sulfuric acid supported on silica-gel, as promising method for facile, high yielding, regioselective syntheses of mononitrated polycyclic aromatic hydrocarbons, 6-nitrochrysene, 1-nitropyrene, 1-nitronaphthalene, 2-nitrofluorene, 3-nitrofluoranthene, and 9-nitroanthracene.     

气相色谱/质谱法测定熏肉中的多环芳烃

建立了熏肉中多环芳烃的气相色谱/质谱(GC/MS)测定方法。样品经正己烷-丙酮(体积比为1∶1)超声波提取、氧化铝柱净化后,用GC/MS分离测定。优化了25种多环芳烃(PAHs)化合物的分离测定条件。结果 25种PAHs回收率范围为48.5%-106.5%;日内(n=7)相对标准偏差为3.75%-7.95%。方法具有灵敏度高、准确度好、能同时分离测定20余种多环芳烃化合物的优点,适合于熏肉中多环芳烃化合物的分析测定。     

Fast Atom Bombardment Combined with Mass Spectrometry or Characterization of Polycyclic Aromatic Hydrocarbons

A new approach using fast atom bombardment combined with mass spectrometry to characterize polycyclic aromatic hydrocarbons (PAHs) in the range of 128–252 u molecular weight is described. Sulfolane was employed as a liquid matrix for these π-conjugated hydrocarbons. Bombardment of sulfolane solution of certain PAHs with an atom beam produces both radical cation (M⁺) and protonated molecule [(M + H)⁺], with no evidence of fragmentation. Collisional activation of the fast atom bombardment-desorbed M⁺ ions, however, results in several structure-specific fragment ions. Structural differences in a few isomeric hydrocarbons can be detected using the [(M + H)⁺]/[M⁺] abundance ratio and in the pyrene-fluoranthene pair by the B/E linked-field-collision-activated dissociation data. The [(M + H)⁺]/[M⁺] was found to be compound-specific and correlated well with certain properties (resonance energy, proton affinity, and ionizing energy) of PAHs.     

色谱／质谱联用技术分析测定贻贝中的多环芳烃

介绍了ＧＣ－ＭＳ联用技术－物质征离子选择法测定贻贝中多环芳烃的分析方法，并就定性定量离子的选择，以及方法的准确度和精密度进行了探讨。结果表明，本方法适用于海洋生物贻贝，牡蛎中ＰＡＨｓ的分析测定。     

气相色谱-质谱法测定塑料制品中多环芳烃

将正己烷-二氯甲烷(2+1)混合溶剂加入于塑料样品中,在水浴中于室温下超声萃取30 min,所得溶液在控温30℃的水浴中用旋转蒸发浓缩至2 mL,并将此溶液通过硅胶柱净化分离.先用正己烷淋洗硅胶柱以洗去非极性的正构烷烃,然后以正己烷-二氯甲烷(3+2)混合溶剂淋洗,所得洗脱液先经旋转蒸发浓缩至2 mL,再用氮气吹拂浓缩至恰为1.0 mL,此溶液供气相色谱-质谱分析之用,对相应的分析条件也作了详述.由于采用了先旋转蒸发后氮气吹拂的浓缩方法,不仅使蒸发时间缩短,而且减少了低沸点多环芳烃(PAH)的挥发损失.按所提出的方法测定了塑料中16种PAH,方法的检出限(3S/N)小于0.01 mg·kg-1.选用一种含PAH甚少的塑料样品作为基体,加入3个浓度水平含16种PAH的混合标准溶液按方法操作进行回收试验,测得回收率在87.2%～100.2%之间,测定值的相对标准偏差(n=7)在1.3%～5.8%之间.     

气相色谱-串联质谱法测定牛奶中多氯联苯及多环芳烃

建立了快速测定牛奶中20种多氯联苯(PCBs)和多环芳烃(PAHs)的气相色谱-串联质谱(GC-MS/MS)分析方法。目标化合物用正己烷提取3次,Cleanert Ba P-SPE固相萃取柱净化,GC-MS/MS测定。结果表明,20种目标物在5~200μg/L范围内呈良好线性,线性相关系数均大于0.99,方法定量下限为1.0μg/kg。在1.0,2.0,5.0μg/kg 3个加标水平下的平均回收率为67.3%~106.9%,相对标准偏差(RSD)为3.1%~13.9%。该方法简便、快速、准确,可用于牛奶中多氯联苯和多环芳烃残留的检测,为牛奶的质量控制和安全评价提供了保证。     

Micellar Extraction of Polycyclic Aromatic Hydrocarbons from Certified Marine Sediment

Abstract

In the present study the extraction of polycyclic aromatic hydrocarbons from a certified marine sediment (SRM 1941a) with a micellar medium of polyoxyethylene 10 lauryl ether by micro-wave- and ultrasound-assisted method has been evaluated. The analysis of extracts has been carried out by HPLC with fluorimetric detection and wavelength programming. Hydrocarbons with more than three rings gave average recoveries of 77.4% and 86.5%, by microwave- and ultrasound-assisted methods respectively, with a mean relative standard deviation better than 6.2%.     

Analysis of Parent/Nitrated Polycyclic Aromatic Hydrocarbons in Particulate Matter 2.5 Based on Femtosecond Ionization Mass Spectrometry

Particulate matter 2.5 (PM2.5), collected from ambient air in Fukuoka City, was analyzed by gas chromatography combined with multiphoton ionization mass spectrometry using an ultraviolet femtosecond laser (267 nm) as the ionization source. Numerous parent polycyclic aromatic hydrocarbons (PPAHs) were observed in a sample extracted from PM2.5, and their concentrations were determined to be in the range from 30 to 190 pg/m³ for heavy PPAHs. Standard samples of nitrated polycyclic aromatic hydrocarbons (NPAHs) were examined, and the limits of detection were determined to be in the picogram range. The concentration of NPAH adsorbed on PM2.5 in the air was less than 900–1300 pg/m³.

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Graphical Abstract ?

     

气相色谱-串联质谱法测定土壤中多环芳烃和多氯联苯

研究土壤中持久性有机污染物的含量可以为区域环境治理和来源解析提供基础数据。本文通过固相萃取结合气相色谱-串联质谱法建立了16种多环芳烃和15种多氯联苯的检测方法,并优化了固相萃取净化方法、色谱条件以及质谱碰撞能量。结果表明16种多环芳烃和15种多氯联苯的标准曲线线性关系良好,方法线性相关系数r~20.999,方法的检出限为0.1~2.5μg·kg~(-1),16种多环芳烃的平均加标回收率范围为62.5%~113.5%,相对标准偏差在2.3%~8.2%之间,15种多氯联苯的平均加标回收率范围为62.6%~91.4%,相对标准偏差在5.2%~7.8%之间。方法的准确度和精密度较高,通过对实际样品的测定,说明该方法具有较低的检出限及较强的抗干扰能力,能满足土壤中多环芳烃和多氯联苯的检测要求。     

Computational Studies on the Reactivity of Polycyclic Aromatic Hydrocarbons

Polycyclic aromatic hydrocarbons (PAHs) are widely present in the environment as toxic pollutants. In this study, quantum chemistry methods are used to study reactions of PAHs in both particle and gas phases. Seven theoretical methods are exploited to predict the reactive sites of 15 PAHs in the particle phase. Among these methods, the performance of the condensed Fukui function (CFF) is optimum. The gas-phase reactions of eight PAHs are also investigated. Except for fluorene, CFF predicts correctly the gas-phase mono-nitro products for seven systems. The products of fluorene predicted by CFF are 1-nitrofluorene and 3-nitrofluorene, which is however inconsistent with the experimental results. Transition state theory is then used to investigate the reaction mechanism of fluorene. Calculated rate constants for 3-nitrofluorene and 2-nitrofluorene formation are much bigger than that for 1-nitrofluorene formation, which is in agreement with the experimental results.     

Structural Characterization of Polymers by MALDI Spiral-TOF Mass Spectrometry Combined with Kendrick Mass Defect Analysis

High-resolution mass spectrometry (HRMS) continues to play an important role in the compositional characterization of larger organic molecules. In the field of polymer characterization, however, the application of HRMS has made only slow progress because of lower compatibility between matrix-assisted laser desorption/ionization (MALDI) and ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICRMS). In this study, a newly developed type of MALDI high-resolution time-of-flight mass spectrometry (TOFMS) with a spiral ion trajectory (MALDI spiral-TOFMS) was applied to the structural and compositional characterization of polymers. To create a graphical distribution of polymer components on a two-dimensional plot converted from complex mass spectra, we adopted a slightly modified Kendrick mass defect (KMD) analysis based on accurate masses determined using spiral-TOFMS. By setting the Kendrick mass scale based on the mass of the repeating units of a given polymer, components with common repeat units lined up in the horizontal direction on the KMD plot, whereas those components with different structures were shifted vertically. This combination of MALDI spiral-TOFMS measurement and KMD analysis enabled the successful discrimination of the polymer components in a blend of poly(alkylene oxide)s, the compositional analysis of poly(ethylene oxide)/poly(propylene oxide) block copolymers, and profiling of the end-group distribution of poly(ε-caprolactone)s synthesized under different conditions.

Relationship between the Biodegradability and Structure of Polycyclic Aromatic Hydrocarbons

21 Physicochemical and quantum chemical parameters of 17 kinds of polycyclic aromatic hydrocarbons were calculated by using semi-empirical MOPAC AM1 method. By means of Partial Least Squares （PLS）, quantitative structure-biodegradation relationship （QSBR） study was performed with the logarithm of specific biodegradation rates （logKb）. The optimal model was obtained, and the result showed that the first-order molecular connectivity index （^1X）, the energy of the lowest unoccupied molecular orbital （Elumo）, logarithm of n-octyl alcohol/water partition coefficient （logP） and torsion energy （Et） are the dominant factors governing the biodegradability of polyeyelie aromatic hydrocarbons, and the effect of second-order valence molecular connectivity index （^2X^V）, the third-order valence molecular connectivity index （^3X^V） and molar refractivity （Rm） should not be ignored.     

Determination of Polycyclic Aromatic Hydrocarbons in Biodiesel Exhaust from Jatropha curcas and Chlorella variabilis by Gas Chromatography with Flame Ionization Detection

Biodiesel serves as a promising alternative to the conventional petroleum fuels and is considered to be a renewable source of energy which can be used in compression-ignition engines with minimum or no modifications. Two biodiesels derived from Jatropha curcas seeds and marine microalga Chlorella variabilis were substituted for petrodiesel and 16 priority polycyclic aromatic hydrocarbons (United States Environmental Protection Agency) were targeted for quantification through gas chromatography equipped with a flame ionization detector. For comparison, petrodiesel was selected as a control, and the analyte concentrations were calculated through calibration curves with correlation coefficient ranging from 0.9909 to 0.9999. The analytical figures of merit were determined for each analyte. The relative standard deviations for intra-day repeatability and inter-day reproducibility were in the range of 4.47–8.75%. The results indicated a significant decrease of around 77 and 68% in the overall polycyclic aromatic hydrocarbon concentrations in the particulate matter originating from J. curcas and microalga C. variabilis biodiesel, respectively. This study is perceived as an important step toward describing the green emission behavior of these biodiesels and their merits compared to the conventional petroleum-based fuels.