250 nm激光诱导土壤中多环芳烃的荧光检测系统

为了提高激光诱导荧光(Laser-Induced Fluorescence,LIF)方法对土壤中多环芳烃(Polycyclic Aromatic Hydrocarbons,PAHs)检测的精度,以蒽、芘、菲三种多环芳烃的标准土壤混合物作为样本,通过紫外吸收光谱研究了这三种物质的最佳激发波长为250 nm,主要采用ND6000可调谐染料激光器、500is-sm型三光栅光谱仪和DK734-18F型ICCD构建了LIF方法测量土壤中多环芳烃的检测系统。在250 nm激光激发下,这三种PAHs的土壤混合样本的荧光发射光谱满足各自特征发射光谱,不同质量分数和其荧光强度线性相关系数达到0.97以上。实验结果表明该检测系统提高了对土壤中PAHs的检出限和线性相关性。     

HPLC—荧光检测测定五种多环芳烃

本文采用HPLC—荧光检测测定五种多环芳烃化合物。在shim-pack CLC-ODS柱上,以70％的乙腈水溶液作流动相,20min内同时分离测定了(艹屈)、苊、蒽、荧蒽、芘等五种多环芳烃。     

高效液相色谱荧光法测定土壤中16种多环芳烃

本文介绍了采用高效液相色谱、荧光检测器测定土壤中16种多环芳烃。通过对液相色谱柱的选择、色谱条件、荧光激发和发射波长等条件的优化,实现16种多环芳烃完全分离。特别是对16种多环芳烃的激发和发射波长进行选择,进一步提高检测灵敏度、选择性,降低了干扰。在优化的实验条件下,荧光检测器的检出限为0.09～1.57ng/mL,样品加标回收率为86%-108%。     

HPLC测定鄱阳湖湿地土壤中15种多环芳烃

测定鄱阳湖湿地土壤中多环芳烃的含量,采用丙酮+正己烷(1∶1)为提取溶剂,超声提取40 min,总溶剂量为70 m L(10 g样品),色谱条件为进样量为20μL、流量为1 m L/min、柱温30℃,采用适当的流动相梯度淋洗程序与荧光检测器波长变换程序,高效液相色谱法测定鄱阳湖湿地土壤中15种多环芳烃的含量。结果表明:鄱阳湖湿地土壤中15种多环芳烃的含量为(ng/g):萘,92.45;苊,未检出;芴,9.90;菲,91.75;蒽,119.67;荧蒽,未检出;芘,81.51;苯并(a)蒽,13.26;,6.79;苯并(b)荧蒽,4.53;苯并(k)荧蒽,7.76;苯并(a)芘,未检出;二苯并(a,h)蒽,7.74;苯并(g,h,i)苝,未检出;茚苯(123-cd)芘,未检出。该方法的加标回收率在76.8%~115.1%之间,相对标准偏差在1.3%~5.8%之间,具有良好的准确度和精密度。说明该文建立的方法可测定鄱阳湖湿地土壤中多环芳烃的含量,为进一步研究鄱阳湖湿地土壤中多环芳烃的污染特征与来源解析提供依据。     

反相高效液相色谱法测定土壤中的十五种多环芳烃

本文采用超声披提取、悌度冼脱及二极管阵列检测器和荧光检测器联用的反相高效液相色谱法测定土壤中的多环芳烃,方法简单、快速、准确、灵敏度高,能满足土壤中PAHs的检测要求。对15种PAHs,其荧光检测器的检测限介于0．01—50ng/mL之间,RSD介于2．3％～7．9％之间,回收率介于75％～90％之间。     

竹炭固相萃取恒波长同步荧光法快速测定九龙江水样中的多环芳烃

建立了竹炭固相萃取-恒波长同步荧光法检测九龙江水样中多环芳烃(PAHs)。通过实验综合分析,选定正己烷为洗脱溶剂,洗脱溶剂体积为10m L,上样速率为5 m L/min,上样体积为555m L。采用恒波长同步荧光法对多环芳烃进行定性定量,相关系数r0.99901,检出限在0.0080-0.90 ng·m L-1,相对标准偏差为1.22%-4.20%。此方法应用于测定了龙岩市省控断面九龙江水体中的多环芳烃(PAHs)。水样的加标回收率在98.9%-110.4%该分析方法简便、快速,适用于水体中多环芳烃的分析检测。     

固相萃取富集—高效液相色谱法分析水中多环芳烃(PAHs)

采用固相萃取与高效液相色谱联用技术,测定了水中的多环芳烃。实验中使用Supelco固相萃取过滤装置和Supelco C_(18)固相萃取小柱,100％的甲醇作为流动相。对于萤蒽(FLU),苯并(b)萤蒽(BbF),苯并(K)萤蒽(BkF),苯并(ghi)(BPer)及茚并(1,2,3-cd)芘(IP)的检测限分别为4.1,3.8,1.6,14.4,和3.8ng/L。     

土壤中多环芳烃分析方法研究进展

近年来,环境保护部门要求各地对全国农村土壤质量和场地土壤污染状况展开调查,选择合适的多环芳烃分析方法尤为重要。用于土壤中多环芳烃的提取方法目前主要有索氏提取法、超声提取法、超临界流体萃取、微波辅助萃取、加压流体萃取等方法。高污染的提取物通常需要使用多种净化方法。检测多环芳烃的方法主要有薄层层析荧光光度法、高效液相色谱法、气相色谱质谱法。其中高效液相色谱法可获得较低的检出限,气相色谱质谱法定性能力较好,可排除假阳性。在实际应用过程中,应根据土壤性质和限值要求选择合适的检测方法。     

ABS塑料玩具中多环芳烃风险分析及建议

通过对广州市售的ABS塑料儿童玩具的多环芳烃含量的风险分析实验,汇总有关ABS塑料中多环芳烃含量、毒性资料和测试结果,参考德国、美国EPA、欧盟和中国塑料制品中多环芳烃检测标准。分析ABS塑料儿童玩具中残留的多环芳烃的潜在风险性。     

生物微流控PCR荧光芯片微通道动态检测系统研究

研究和建立了生物微流控PCR荧光芯片微流控微通道动态检测系统,对该系统的多光路光纤校准进行了研究,获得了荧光检测的重复性(偏差:2.6%)和稳定性(偏差》2.7%)等.实验结果表明:该系统可用于准分子激光制备高聚物基生物微流控PCR荧光芯片最佳工艺激光制备参数的优化设计;可用于生物微流控PCR荧光芯片生物分析时的实时荧光定量检测;也可用于对激光荧光检测微型化技术与生物芯片光谱检测集成化提供多功能实验基础和性能评估体系.     

Biodegradation of aged polycyclic aromatic hydrocarbons (PAHs) by microbial consortia in soil and slurry phases

Microbial consortia isolated from aged oil-contaminated soil were used to degrade 16 polycyclic aromatic hydrocarbons (15.72 mgkg(-1)) in soil and slurry phases. The three microbial consortia (bacteria, fungi and bacteria-fungi complex) could degrade polycyclic aromatic hydrocarbons (PAHs), and the highest PAH removals were found in soil and slurry inoculated with fungi (50.1% and 55.4%, respectively). PAHs biodegradation in slurry was lower than in soil for bacteria and bacteria-fungi complex inoculation treatments. Degradation of three- to five-ring PAHs treated by consortia was observed in soil and slurry, and the highest degradation of individual PAHs (anthracene, fluoranthene, and benz(a)anthracene) appeared in soil (45.9-75.5%, 62-83.7% and 64.5-84.5%, respectively) and slurry (46.0-75.8%, 50.2-86.1% and 54.3-85.7%, respectively). Therefore, inoculation of microbial consortia (bacteria, fungi and bacteria-fungi complex) isolated from in situ contaminated soil to degrade PAHs could be considered as a successful method.     

Supercritical CO(2) extraction of PAHs on spiked soil Co-solvent effect and solvent regeneration by ozonization

The supercritical CO(2) extraction of four PAHs (acenaphthene, phenanthrene, anthracene and fluoranthene) from an artificially contaminated soil has been investigated. The effect of temperature (40-60 degrees C), pressure (300-500 bar) and extraction time (90-150 min) has been assessed by conducting a Box-Behnken experimental design. The results suggest the existence of perturbation variables other than the aforementioned controlled variables leading to a significant dispersion of extraction recoveries. With the exception of anthracene, an optimum in temperature (50 degrees C) is envisaged when extracting the PAHs. Analogously, with the exception of anthracene (positive effect), pressure does not have a significant influence. The recovery yield increases as extraction time is increased to a value of 120 min. No further improvement is experienced thereafter. If a co-solvent is used (H(2)O(2) aqueous solution) a beneficial effect can be noticed. Hydrogen peroxide concentration did exert no significant influence in the process. Methanol used to collect the extracted PAHs could be regenerated by gaseous ozone and reused in several consecutive runs.     

Supersensitive detection of sodium in water with use of dual-pulse laser-induced breakdown spectroscopy

Laser-induced breakdown spectroscopy has been used to detect sodium (Na) in water. Laser-induced breakdown was formed by dual-pulse and crossed beam Nd:YAG lasers on a water film. To improve the detection sensitivity, the fluorescence intensity dependence on timing between laser pulses, the delay time of fluorescence detection timing, the gate width of fluorescence detection period, and the laser energy were investigated. Under the optimized conditions, the detection limit of Na in water was achieved in the range of 0.1 parts per billion. The developed system is applicable for quick and supersensitive detection of Na atoms in water.     

Degradation of polycyclic aromatic hydrocarbons by the Chilean white-rot fungus Anthracophyllum discolor

The degradation of three- and four-ring polycyclic aromatic hydrocarbons (PAHs) in Kirk medium by Anthracophyllum discolor, a white-rot fungus isolated from the forest of southern Chile, was evaluated. In addition, the removal efficiency of three-, four- and five-ring PAHs in contaminated soil bioaugmented with A. discolor in the absence and presence of indigenous soil microorganisms was investigated. Production of lignin-degrading enzymes and PAH mineralization in the soil were also determined. A. discolor was able to degrade PAHs in Kirk medium with the highest removal occurring in a PAH mixture, suggesting synergistic effects between PAHs or possible cometabolism. A high removal capability for phenanthrene (62%), anthracene (73%), fluoranthene (54%), pyrene (60%) and benzo(a)pyrene (75%) was observed in autoclaved soil inoculated with A. discolor in the absence of indigenous microorganisms, associated with the production of manganese peroxidase (MnP). The metabolites found in the PAH degradation were anthraquinone, phthalic acid, 4-hydroxy-9-fluorenone, 9-fluorenone and 4,5-dihydropyrene. A. discolor was able to mineralize 9% of the phenanthrene. In non-autoclaved soil, the inoculation with A. discolor did not improve the removal efficiency of PAHs. Suitable conditions must be found to promote a successful fungal bioaugmentation in non-autoclaved soils.     

Investigation of the utility of laser-secondary neutral mass spectrometry for the detection of polyaromatic hydrocarbons in individual atmospheric aerosol particles

The distribution of polyaromatic hydrocarbons (PAHs) in ambient aerosol particles is of importance to both human health and climate forcing. Although time-of-flight secondary ion mass spectrometry (ToF-SIMS) has proven useful for studying the distribution of organic compounds in individual aerosol particles, it is difficult to detect PAHs at relevant concentrations in individual aerosol particles because of their low ion yield. In this study, we explore the potential of using laser secondary neutral mass spectrometry (Laser-SNMS) to study three PAHs: pyrene, anthracene, and naphthalene. Because of the high volatility of PAHs, a cryostage was required for the analysis to prevent sublimation of the molecules into the vacuum chamber. We studied two laser systems, a 157 nm excimer laser, which is capable of single-photon ionization of the PAHs, and a 193 nm laser, which requires multiphoton ionization. Under optimized conditions for laser power density and primary ion pulse length, 193 nm postionization resulted in a 2-50-fold increase in ion yield over ToF-SIMS. Using the 157 nm laser, the yield was increased by more than 3 orders of magnitude for all 3 PAHs studied. The single-photon postionization process proved superior in terms of both yield enhancement and reduced fragmentation. By using the optimized 157 nm laser system and a cryostage, we were able to detect PAHs on the surface of 2 μm diameter ambient aerosol particles.     

Polycyclic aromatic hydrocarbons sorption on soils: some anomalous isotherms

The sorption of four polycyclic aromatic hydrocarbons (PAHs), namely acenaphthene (Ac), phenanthrene (Ph), anthracene (An), and fluoranthene (Fl), on soil has been investigated. The kinetics of the sorption is characterised by the presence of two distinct periods. A fast initial stage followed by a second slower sorption process. Various kinetic models (i.e., Elvoich, Lagergren, second order and double exponential models) have been used to fit experimental data. The sorption equilibrium of individual PAHs has been assessed in the 298-333 K temperature range. Unlike Ac, Ph at 333 K and An and Fl at any temperature showed anomalous isotherms. The reason seems to rely on the "trapping" of dissolved PAHs by soil organic matter (SOM) released to water. This abnormal trend was not experienced when the isotherms were obtained for four PAHs mixture. Apparently, the most soluble Ac was capable of binding all the released material so no effect was thereafter observed.     

Particle-phase dry deposition and air-soil gas exchange of polycyclic aromatic hydrocarbons (PAHs) in Izmir, Turkey

Ambient air and dry deposition samples were collected at suburban and urban sites in Izmir, Turkey. Atmospheric total (particle+gas) ∑(14)PAHs concentrations were 36±39 and 144±163 ng m(-3) for suburban and urban sites, respectively. Phenanthrene was the most abundant compound at all sites, and all samples were dominated by low molecular weight PAHs. Average particulate ∑(14)PAH dry deposition fluxes were 8160±5024 and 4286±2782 ng m(-2) day(-1) and overall average particulate dry deposition velocities were 1.5±2.4 and 1.0±2.3 cm s(-1) for suburban and urban sites, respectively. Soil samples were collected at suburban site. Average soil concentration for ∑(14)PAH was 55.9±14.4 ng g(-1) dry weight. Calculated gas-phase air-soil exchange fluxes indicated that fluorene, phenanthrene, anthracene, and carbazole were deposited to soil in winter while they were volatilized in summer. Other compounds (fluoranthene-benzo[g,h,i]perylene) were deposited to soil in both periods. Annual average fluxes of PAHs representing soil to air (i.e., gas volatilization) and air to soil transfer (i.e., gas absorption, dry deposition, and wet deposition) processes were also compared. All processes were comparable for Σ(14)PAHs however their input was dominated by gas absorption. Gas absorption dominated for lower molecular weight PAHs, however dry deposition dominated for higher molecular weight PAHs. The results have suggested that for fluorene, soil and air may be approaching a steady state condition. For the remaining compounds, there was a net accumulation into the soil.     

Chemometrics-assisted excitation-emission fluorescence spectroscopy on nylon membranes. Simultaneous determination of benzo[a]pyrene and dibenz[a,h]anthracene at parts-per-trillion levels in the presence of the remaining EPA PAH priority pollutants as interferences

This work presents a novel approach for the simultaneous ultratrace determination of benzo[ a]pyrene and dibenzo[ a,h]anthracene, the two most carcinogenic polycyclic aromatic hydrocarbons (PAHs), in a very interfering environment, combining the recently discovered ability of the nylon membrane to strongly retain and concentrate PAHs on its surface, the sensitivity of molecular fluorescence, and the selectivity of second-order chemometric algorithms. The fluorescence excitation-emission matrices, directly measured on a nylon-membrane surface, are processed by applying parallel factor analysis (PARAFAC) and unfolded partial least-squares coupled to residual bilinearization (U-PLS/RBL). The superiority of U-PLS/RBL to quantify BaP and DBA at concentrations below 10 ng L (-1) in the presence of the remaining 14 US EPA (United States Environmental Protection Agency) PAHs at total concentrations ranging from 1400 and 14,000 ng L (-1) is demonstrated. The present method successfully faces this complex challenge without using organic solvents, which are to known produce environmental contamination. Finally, the high sensitivity of the present method avoids preconcentration and elution steps, considerably decreasing the analysis time and the experimental errors. Because the instrumental involved in the determination is nonsophisticated, the experiments could be carried out in routine laboratories.     

Three-way analysis of fluorescence spectra of polycyclic aromatic hydrocarbons with quenching by nitromethane

The application of trilinear decomposition (TLD) to the analysis of fluorescence excitation-emission matrices of mixtures of polycyclic aromatic hydrocarbons (PAHs) is described. The variables constituting the third-order tensor are excitation wavelength, emission wavelength, and concentration of a fluorescence quencher (nitromethane). The addition of a quencher to PAH mixtures selectively reduces the fluorescence intensity of mixture components according to the Stern-Volmer equation. TLD allows the three-way matrix to be decomposed to give unique solutions for the excitation spectrum, emission spectrum, and quenching profiles for each component. The availability of spectra and calculated Stern-Volmer constants can aid in the identification of unknown components. Preprocessing of the data to correct for Rayleigh/Raman scatter and primary absorption by the quencher is necessary. Both three-component (anthracene, pyrene, 1-methylpyrene) and four-component (fluoranthene, anthracene, pyrene, 2,3-benzofluorene) synthetic mixtures are successfully resolved by TLD using quencher concentrations up to 100 mM. Results are compared using both alternating least-squares and direct trilinear decomposition algorithms. The reproducibility of extracted Stern-Volmer constants is determined from replicate experiments. To illustrate the application of TLD to a real sample, a chromatographic cut from the analysis of a light gas oil sample was used. Analysis of the TLD extracted spectra and quenching constants suggests the presence of three classes of polycyclic aromatic hydrocarbons consistent with data from a second dimension of chromatography and mass spectrometry.