固相萃取技术富集水中的多环芳烃

本文系统地研究了淋洗剂强度、用量和有机改性剂的加入对固相萃取水中多环芳烃回收率的影响。研究表明,二氯甲烷和苯的洗脱效果较好,回收率为86％-99％;当淋洗剂的用量超过1．5ml时,对多环芳烃的回收率没有明显的影响,向自来水样中加入20％有机改性剂可明显改善多环芳烃的回收效果,使回收率达到89％-102％。     

固相圆盘萃取(SPE-disk)技术富集水中多环芳烃的方法研究

系统研究了影响圆盘萃取效率的因素,发现洗脱剂的合理选择至关重要,同时获得了最优化的样品处理条件。     

固相萃取——高效液相色谱法测定水中多环芳烃

【目的】采用固相萃取——高效液相色谱法测定水中多环芳烃。【方法】介绍水中7种多环芳烃的高效液相色谱测定方法,探讨各种条件对测定的影响,从固相萃取柱、洗脱溶剂、洗脱体积、有机改性剂等方面优化测定条件。【结果】优化得到的固相萃取条件为:选择Oasis HLB固相萃取色谱小柱,洗脱溶剂为二氯甲烷,洗脱体积为2mL,分2次洗脱,并在水样中加入20%的甲醇作为有机改性剂。使用该方法的加标回收率为89.9%-105.5%,相对标准偏差为1.4%——4.3%,检出限为1-40ng/L【结论】固相萃取——高效液相色谱法不仅各组分的回收率和灵敏度高,而且具有操作简便、溶剂用量少的特点,符合水中多环芳烃测定的要求。     

利用固相萃取技术检测环境水样中多环芳烃的方法

综述了利用固相萃取柱、固相萃取膜、固相微萃取三种固相萃取技术检测环境水样中多环芳烃的方法,并对其发展趋势进行了展望.     

固相膜萃取-气相色谱/离子阱质谱法测定水中17种多环芳烃

利用固相萃取膜富集,气相色谱-离子阱质谱联用法测定水中17种多环芳烃。通过实验表明,该方法操作简便,灵敏度高,精密度好,采用气质联用技术,内标法测定,定性、定量准确。用该方法测定实际样品,平均回收率为80%～113%,17种多环芳烃的方法检出限为0.07～0.23μg/L。     

固相萃取技术富集水中酚类的影响因素探讨

采用固相萃取—高效色谱法测定水中酚类.通过正交实验和验证试验探讨固相萃取技术富集水中7种酚类各种因素的影响,优化固相萃取的条件.优化得到的固相萃取条件为：样品pH为2,选择Oasis HLB固相萃取色谱小柱,流速为：5 mL/min,洗脱溶剂为四氢呋喃,洗脱体积为2mL,分2次洗脱.所建立的方法具有回收率高、操作简便、溶剂用量少的特点.     

柱床干燥处理对固相萃取法富集水中多环芳烃类有毒物质脱附效率的影响

系统介绍了柱床干燥处理对 Ｃ１８ 键合相富集柱萃取水中多环芳烃脱附效率的影响, 并就最佳干燥时间的选择进行了讨论。     

固相萃取-液相色谱法分析监测九龙江流域的多环芳烃

采用固相萃取与高效液相色谱-二极管阵列检测联用(spe-HPLC-PDA)技术,建立了河水中12种微量多环芳烃(PAHs)的快速分析方法。选取C18为固相萃取小柱,经优化检测条件,PAHs在0.05~50μg/m L浓度范围内,线性相关系数在0.9991~0.9999,检出限0.016~0.583μg/L,加标回收率为83%~115%。该法用于龙岩市省控断面九龙江河水中PAHs实时监测,结果显示全年流域河水PAHs的平均分布值为109.60μg/L,在分布上呈现典型的时空分异特征。     

原位制备复合碳纳米粒涂层用于环境水样中多环芳烃的高效固相微萃取

通过阳极氧化法在镍钛(NiTi)丝上原位生长了双金属纳米粒(Ni Ti ONPs)层,后通过水热法和碳化处理制备了具有复合碳纳米粒涂层的纤维(NiTi@NiTiONPs@C纤维)。将其与高效液相色谱-紫外检测器(HPLC-UV)联用研究了其对多环芳烃(PAHs)的萃取性能。与其他纤维相比,NiTi@NiTiONPs@C纤维对PAHs有更好的萃取性能。在优化条件下,PAHs的线性范围为0.05～200g·L-1,LODs介于0.006g·L-1和0.127g·L-1之间。日内和日间分析的RSDs分别为4.17%～5.94%和5.71%～7.13%。实际水样的加标回收率为86.60%～112.0%。     

Indoor Polycyclic Aromatic Hydrocarbon Concentration in Central India

The indoor burning of different materials like fuels, incense, mosquito coil, candles etc. results in generation of polycyclic aromatic hydrocarbons (PAHs) in an uncontrolled manner. The PAH, i.e., Benzo(a)pyrene (BaP) is considered as most toxic or carcinogenic and the toxicity of other PAHs is related to this compound. Therefore, the concentration and emission fluxes of polycyclic aromatic hydrocarbons (PAHs) emitted during burning of commonly used indoor materials, i.e., 15 fuels (i.e., biomass (BM), coal (C), cow dung (CD), kerosene (K)), 4 incense (IS) and mosquito coil (MC) in Raipur district, Chhattisgarh, central India is described. The samples were taken in September 2013 in indoor environments and respective smoke emitted were collected using high volume United State of America (USA) air sampler on quartz fiber filters. The concentration of total 13 PAHs (∑PAH₁₃) (i.e., phenanthrene, anthracene, fluoranthene, pyrene, benz(a)anthracene, chrysene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)-pyrene, dibenz(ah)anthracene, benzo(ghi) perylene, indeno1,2,3-(cd)pyrene, and coronene) in particulate matter (PM₁₀) in the indoor air during burning of the fuels, IS and MC materials ranged from 367–92052 ng m^?3, 4089–14047 ng m^?3, and 66–103 ng m^?3 with mean values of 7767 ± 11809 ng m^?3, 9977 ± 4137 ng m^?3, and 74 ± 20 ng m^?3, respectively. The mean concentration of the ∑PAH₁₃ present in indoor environment is much higher than the WHO limit value of 1.0 ng m^?3. The sources and toxicities of PAHs are discussed.     

Seasonal Influence on Vapor-and Particle-Phase Polycyclic Aromatic Hydrocarbon Concentrations in School Communities Located in Southern California

Ambient concentrations of 15 vapor-and particle-phase (PM _2.5 ) polycyclic aromatic hydrocarbons (PAHs), listed by the US EPA as priority pollutants, were measured between July 2002 and November 2003 in six Southern California communities participating in a multi-year chronic respiratory health study of schoolchildren. The communities were geographically distributed over two hundred kilometers, extending from Long Beach in coastal Los Angeles, to high mountain areas to the north and west of the Los Angeles basin, and south into Eastern San Diego County. Seasonal and spatial variation in the atmospheric concentrations of PAHs is of interest because this class of compounds includes potent mutagens, carcinogens, and species capable of generating reactive oxygen species (ROS) that may lead to oxidative stress. Naphthalene accounted for 95% of the total PAH mass; annual averages ranged from 89 to 142 ng m ^{? 3} . Benzo[ghi]perylene (BGP) and the pro-carcinogen benzo[a]pyrene (BAP), present almost exclusively in the particle-phase, ranged respectively from 38 to 231 pg m ^?3 and 75 and 111 pg m ^{? 3} , with the highest values observed in Long Beach, a community with a high volume of seaport-related activities, and Lancaster, a commuter dormitory community. A considerable increase in the particle-phase PAH concentration, relative to the vapor-phase, was observed as ambient temperature decreased. Cold/hot season ratios for PAHs in PM _2.5 averaged 5.7, reaching 54 at Long Beach. The presented data underscore the importance of seasonal variations on atmospheric PAH concentrations. These observations are relevant to future interpretation and analysis of community-scale human health effects research.     

Identification of Methylene-Bridged Polycyclic Aromatic Hydrocarbon Products of Catechol Pyrolysis

As methylene-bridged polycyclic aromatic hydrocarbons (PAH) are known for their carcinogenicity and occurrence in solid-fuel byproducts and environmental samples, we have employed high-pressure liquid chromatography with diode-array ultraviolet- visible absorbance and mass spectrometric detection (HPLC/UV/MS) to search for methylene-bridged PAH among the products of the laboratory-scale pyrolysis of cate- chol, a model fuel representing aromatic moieties in coal, tobacco, and plant-based biomass fuels. Utilizing two different octadecylsilica columns and five different mobile- phase separation methods, the HPLC/UV/MS analyses have led to the unequivocal identification of six methylene-bridged PAH among the products of catechol pyrolysis at 1000°C and 0.3 s in a laminar-flow reactor: the C₁₅H₁₀ 4H-cyclopenta- [def]phenanthrene, the C₁₉H₁₂ 11H-benz[bc]aceanthrylene and 4H-cyclopenta[def]- chrysene, the C₂₁H₁₂ 11H-indeno[2,1,7-cde]pyrene and 4H-benzo[def]cyclopenta[mno]- chrysene, and the C₂₃H₁₂ 1H-benzo[ghi]cyclopenta[pqr]perylene. None of these six methylene-bridged PAH have ever before been identified as pyrolysis products of catechol or of any other pure-component fuel. The mass and UV spectra of two additional catechol pyrolysis product components have been examined in light of the finding that the UV spectra of methylene-bridged PAH generally resemble those of their respective parent benzenoid PAH (but with a 5- to 12-nm bathochromic shift in the p band)—resulting in the identification of a methylene-bridged naphtho[2,1-a]pyrene and the tentative identification of a methylene-bridged naphtho[2,3-a]pyrene, two previously unrecognized C₂₅H₁₄ PAH that would be expected to exhibit significant mutagenic and/or carcinogenic behavior.     

同步荧光法测定河水中的多环芳烃

建立了竹炭固相萃取恒能量同步荧光法测定河水中多环芳烃(PAHs)。优化了实验条件。选定正己烷为洗脱溶剂,洗脱溶剂体积为10 m L,上样速率为5 m L/min,上样体积为555 m L。该方法的检出限在0.185~1.77 ng·m L~(-1)之间,相对标准偏差为2.28%~5.40%,实际水样的加标回收率为95.4%~110.7%。     

Ozonation of Polycyclic Aromatic Hydrocarbons in Water Solution

The degradation of three polycyclic aromatic hydrocarbons (PAHs): benzo[a]pyrene (BAP), chrysene (CHR), and fluorene (FLU) in aqueous solution using ozone was investigated. The influence of pH of the reaction mixture, ozone concentration, and the presence of a radical scavenger on the reaction rate was determined. The highest rate of PAHs disappearance was achieved in acidic solutions. The radical scavenger, tert-butanol, effectively inhibited the rate of PAHs destruction. The rate constants of direct reaction of PAHs with ozone were calculated and they were equal to (3.32 ± 0.21) × 10⁴; (1.10 ± 0.15) × 10⁴ and 44.8 ± 1.1 M^?1s^?1 for BAP, CHR, and FLU, respectively. The contributions of direct ozonolysis, and radical reaction to PAHs oxidation in ozonation processes, were evaluated.     

The Influence of Platinum Addition on Nano-Crystalline Ceria Catalysts for the Total Oxidation of Naphthalene a Model Polycyclic Aromatic Hydrocarbon

Abstract  

The effect of adding Pt to a highly active ceria polycyclic aromatic hydrocarbon total oxidation catalyst has been investigated for the oxidation of naphthalene. The addition of Pt to ceria suppressed the performance of the catalyst for total oxidation. The addition of Pt reduced catalyst surface area, decreased the ceria crystallite size, decreased the concentration of ceria defects and increased the reducibility of the catalyst. The suppression of activity has been attributed to strong metal-support interaction between Pt and ceria, which limits the availability of lattice oxygen for the oxidation process, which follows the Mars-Van Krevelen redox mechanism in the absence of Pt. It is postulated that the presence of dispersed Pt, alters the mechanism of naphthalene oxidation over the ceria catalyst.     

Excitation Dependent Fluorescence Quantum Yield in Hydrocarbon Fuels Containing Polycyclic Aromatic Compounds

Fluorescence emission spectra and quantum yields have been measured for neat sample of six different hydrocarbon fuels over different possible excitation wavelengths. Hydrocarbon fuels show different excitation fluorescence cutoff depending on their commercial use and applications in the UV ～ visible region. The fluorescence emission maximum of these fuels shows a red shift with excitation wavelength. Resonance energy transfer and self-quenching through solvent collision of fluorophores play an important role on the fluorescence characteristics of multifluorophoric mixture like petroleum fuels at higher concentration. The fluorescence quantum yield of these fuels is a function of the excitation wavelength and is different for different fuels. The change in quantum yield with excitation wavelength for petroleum fuels is different from that of crude oils. The change in fluorescence quantum yield at lower excitation wavelength provides a promising tool to estimate contamination of diesel and petrol by kerosene.     

芳烃联合装置优化生产及节能降耗技术措施探讨

针对芳烃联合装置运行的特点,分析了造成芳烃联合装置能耗偏高的原因,提出了优化装置负荷、提高加热炉效率、回收烟气余热等节能降耗措施,从而达到节能降耗目的。