Three-way multivariate calibration procedures applied to high-performance liquid chromatography coupled with fast-scanning fluorescence spectrometry detection. Determination of polycyclic aromatic hydrocarbons in water samples

Three-way partial least-squares and n factor parallel factor analysis have been compared for the analysis of polycyclic aromatic hydrocarbons in water samples. Data were obtained with a chromatographic system set to record short-time chromatograms containing several unresolved peaks. The detection system consisted of a fast-scanning fluorescence spectra detector, which allows one to obtain three-dimensional data, where retention time, emission wavelengths, and fluorescence intensity are represented. The combined use of a multivariate calibration method and the three-dimensional data obtained from the HPLC-FSFS system allows resolution of closely eluting compounds, thus making a complete separation unnecessary. The procedure has been applied to tap water samples (spiked at 0.10 and 0.20 μg L(-)(1) levels) with good results, similar to those obtained with a HPLC system with a conventional fluorescence detector.     

加速溶剂萃取-高效液相色谱法同时测定大气颗粒物PM2.5中16种多环芳烃

建立大气颗粒物PM2.5中16种优控多环芳烃(PAHs)的加速溶剂萃取-高效液相色谱法同时测定方法。用中流量PM2.5采样器,以玻璃纤维滤纸为滤料,以100 L/min的流速连续采样24 h。采样后的玻璃纤维滤纸经正己烷-丙酮(6∶4,ν/ν)于加速溶剂萃取仪中提取,提取液浓缩后用乙腈定容,通过C18色谱柱分离,紫外和荧光检测器检测。16种PAHs在0.20~5.00μg/m L范围内线性相关系数r≥0.999 8,检出限为0.002~0.012μg/m L,方法平均回收率为71.3%~96.5%,相对标准差为0.50%~4.8%。该法简便、快速、准确、灵敏,将其应用于成都市3个区域空气颗粒物PM2.5中16种PAHs的测定,结果理想。     

Determination of polycyclic aromatic hydrocarbons in drinking water samples by solid-phase nanoextraction and high-performance liquid chromatography

A novel alternative is presented for the extraction and preconcentration of polycyclic aromatic hydrocarbons (PAH) from water samples. The new approachwhich we have named solid-phase nanoextraction (SPNE)takes advantage of the strong affinity that exists between PAH and gold nanoparticles. Carefully optimization of experimental parameters has led to a high-performance liquid chromatography method with excellent analytical figures of merit. Its most striking feature correlates to the small volume of water sample (500 microL) for complete PAH analyses. The limits of detection ranged from 0.9 (anthracene) to 58 ng.L (-1) (fluorene). The relative standard deviations at medium calibration concentrations vary from 3.2 (acenaphthene) to 9.1% (naphthalene). The analytical recoveries from tap water samples of the six regulated PAH varied from 83.3 +/- 2.4 (benzo[ k]fluoranthene) to 95.7 +/- 4.1% (benzo[ g,h,i]perylene). The entire extraction procedure consumes less than 100 microL of organic solvents per sample, which makes it environmentally friendly. The small volume of extracting solution makes SPNE a relatively inexpensive extraction approach.     

Thermodynamic and kinetic characterization of polycyclic aromatic hydrocarbons in reversed-phase liquid chromatography

The retention of six polycyclic aromatic hydrocarbons (PAHs) was characterized by reversed-phase liquid chromatography. The PAHs were detected by laser-induced fluorescence at four points along an optically transparent capillary column. The profiles were characterized in space and time using an exponentially modified Gaussian equation. The resulting parameters were used to calculate the retention factors, as well as the concomitant changes in molar enthalpy and molar volume, for each PAH on monomeric (2.7 micromol/m2) and polymeric (5.4 micromol/m2) octadecylsilica. The changes in molar enthalpy become more exothermic as ring number increases and as annelation structure becomes less condensed. The changes in molar volume become more negative as ring number increases for the planar PAHs, but are positive for the nonplanar solutes. In addition, the rate constants, as well as the concomitant activation enthalpy and activation volume, are calculated for the first time. The kinetic data demonstrate that many of the PAHs exhibit very fast transitions between the mobile and stationary phases. The transition state is very high in energy, and the activation enthalpies and volumes become greater as ring number increases and as annelation structure becomes less condensed. The changes in thermodynamic and kinetic behavior are much more pronounced for the polymeric phase than for the monomeric phase.     

Sorption of polycyclic aromatic hydrocarbons on particulate organic matters

Particulate organic matter (POM) is a key organic matter fraction which can influence soil fertility. Its interactions with hydrophobic organic pollutants (HOCs) have not been characterized and the mechanisms of retention of HOCs by POM remain unclear. In the present study, sorption behaviors of polycyclic aromatic hydrocarbons (PAHs) naphthalene (NAP), phenanthrene (PHE), and pyrene (PYR) by POMs separated from different soils were examined and the POMs were characterized by elemental analysis, solid state ¹³C NMR, and Fourier transform infrared spectroscopy (FT-IR). The results indicated that POMs were mainly composed of aliphatic components with high polarity. The different original POMs showed similar chemical composition and configuration. Sorption behaviors of PAHs indicated that there was no significant difference in sorption capacity among the POMs. Sorption of NAP and PHE by POMs displayed a nonlinear isotherm, while sorption of PYR yielded a linear isotherm. No significant hysteresis and ionic strength effect were observed for PAH desorption from the POMs.     

Selective fluorescence quenching of polycyclic aromatic hydrocarbons by aliphatic amines

The ability of primary, secondary, and tertiary mono- and diamines to serve as fluorescence quenchers for polycyclic aromatic hydrocarbons (PAHs) has been evaluated in acetonitrile and methanol. In general, the efficiency of quenching increases with the electron-donating ability of the amine and with the number of amine groups. The selectivity for nonalternant PAHs relative to the alternant isomers appears to decrease as the quenching efficiency increases. Nevertheless, all of the amines exhibit greater selectivity than 1,2,4-trimethoxybenzene, a previously characterized selective quencher for nonalternant PAHs. The experimentally measured rate constants for dynamic quenching show good agreement to those predicted by Rehm-Weller electron-transfer theory in the solvent acetonitrile. In contrast, the rate constants in methanol are anomalously low and do not conform well to Rehm-Weller theory. Presumably this is due to explicit hydrogen bonding between the solvent and quencher, which decreases the concentration of the free amine that is available for fluorescence quenching.     

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.     

Phenyl-modified reversed-phase liquid chromatography coupled to atmospheric pressure chemical ionization mass spectrometry: a universal method for the analysis of partially oxidized aromatic hydrocarbons

A new liquid chromatographic method for the efficient separation of aromatic compounds having a wide range of sizes, molecular structures, and polarities has been developed. Based on a phenyl-modified silica reversed stationary phase and a methanol-water solvent gradient, it allows the separation of mono- and polycyclic aromatic hydrocarbons (PAHs) having up to five condensed aromatic rings and partially oxidized derivatives within a single chromatographic run of 40-min duration. The applicability of the method is demonstrated using 81 reference substances (PAHs, phenols, quinones, acids, lactones, esters, etc.) and real samples of environmental, medical, and technical relevance (ozonized PAHs, lake water, human urine, diesel exhaust condensates). The retention times of the investigated aromatics exhibit a regular increase with molecular mass and a systematic decrease with increasing number and polarity of functional groups. In case of intramolecular hydrogen bonding, a positive shift of retention time provides additional structural information. The combination of chromatographic retention time with the molecular mass and structural information from mass spectrometric detection allows the tentative identification of unknown aromatic analytes at trace levels, even without specific reference substances. With atmospheric pressure chemical ionization (APCI), low detection limits and highly informative fragmentation patterns can be obtained by in-source collision-induced fragmentation in a single-quadrupole LC-APCI-MS system as applied in this study, and multidimensional MS experiments are expected to further enhance the potential of the presented method.     

气相色谱-质谱法测定电子电气产品材料中多环芳烃

本文建立了采用气相色谱-质谱联用检测电子电气产品材料中多环芳烃的方法。以丙酮-正己烷(1+1)为提取溶剂,利用自动索氏提取仪提取电子电气产品材料中多环芳烃,正己烷-二氯甲烷(3+2)混合液淋洗硅胶小柱净化,气相色谱-质谱联用仪检测,该方法检测限在0.2mg/kg,加标回收率在59%～99%之间,相对标准偏差(RSD)小于5%,线性范围在0.1mg/L～100mg/L,相关系数(r)大于0.999。实验结果表明,该方法简便、可靠,能满足电子电气产品材料中多环芳烃的检测要求。     

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。     

GC-MS结合微量QuEChERS法快速测定土壤中16种多环芳烃

为实现土壤样品中典型持久性污染物的快速、灵敏及批量测定,通过基于改进微量-QuEChERS(μ-QuEChERS)技术结合超声辅助方法,且与气相色谱质谱联用(GC-MS)分析,建立土壤中16种多环芳烃(PAHs)快速测定方法。少量土壤(1.0 g)样品经过2.0 mL乙腈与二氯甲烷(V/V=1∶2)辅助15.0 min超声提取后,利用N-丙基乙二胺(PSA)和C18混合分散剂快速涡旋净化,离心、转换溶剂后进行GC-MS外标法测定。结果表明,在2～800μg/L浓度范围内,16种PAHs呈现良好的线性关系,相关系数均在0.992 0以上,检测限(LOD,S/N=3)低于0.50μg/kg。在8.0,20.0,100.0μg/kg加标浓度下,16种PAHs的加标回收率在70.3%～109.1%(n=3)。该方法快速、简单、准确,需样量少、环境污染小,可为土壤中PAHs的快速筛查提供批量检测方法。