Multivariate optimization of a GC-MS method for determination of sixteen priority polycyclic aromatic hydrocarbons in environmental samples

This paper describes the development and optimization, by using multivariate analysis, of a GC-MS-SIM method for evaluation of the 16 polyaromatic hydrocarbons considered as priority pollutants in atmospheric particulate material by the US EPA. In order to assure an adequate separation in the shortest analysis time, a multivariate design was used to set the conditions of the oven temperature program. The optimization process was carried out using factorial fractional design and Box-Behnken design. The following factors were evaluated: initial temperature, temperature rate #1, intermediary temperature, temperature rate #2, and final temperature. The optimized conditions were set at: 70 degrees C (2 min) --> 200 degrees C (30 degrees C/min, 5 min) --> 300 degrees C (5 degrees C/min, 1.67 min). Moreover, we have also optimized the injector temperature as 310 degrees C and sampling time as 0.8 min. The total analysis time was 33 min. Validation of GC-MS-SIM yielded satisfactory results for repetitivity of the detector response and retention times, and linearity of calibration curves. LOD were established as 0.13-0.34 ng/mL (peak area) and 0.18-0.72 ng/mL (peak height). The method has been shown to be appropriate for the analysis of samples of atmospheric particulate material and/or other environmental matrices.     

Reactive matrix clean-up of naturally occurring perylene in young lignite

Young lignite from two locations in Sendai City, Japan, were analyzed for polynuclear aromatic compounds (PACs). Lignite samples were extracted with toluene and PACs were isolated by a compound-class-selective, reactive matrix clean-up. This clean-up separates all compounds of polynuclear aromatic structure, for example hydrocarbons and ketones and their primary metabolites, from interfering organic compounds. The result of this isolation procedure is, therefore, a group of a large number of polycyclic compounds with different functional groups. Further analysis is done by glass capillary gas chromatography. Perylene was identified as the only compound obtained by the reactive matrix clean-up of lignite samples from both locations. Concentrations were in the range of 1–10 mg kg⁻¹. Conversely, PACs resulting from particulate emissions from fossil fuel combustion always contain isomeric PAHs (polynuclear aromatic hydrocarbons) with some polycyclic aromatic ketones and thousands of primary and secondary metabolites at very low concentrations. This was demonstrated for a sample of urban air particulate matter, which is the source of PAC contamination of surface soil. The absence of accompanying PAHs and polynuclear aromatic ketones in the lignite samples confirms that perylene did not originate from a combustion process. It is assumed that the high concentrations of perylene are the result of a reduction of perylene quinone. Thus, the high perylene content of the lignite samples investigated is of biogenic origin.     

磺化杯芳烃修饰的金纳米粒的合成及其对多环芳烃的比色检测

通过偶联修饰的方法合成了水溶性磺化杯芳烃修饰的金纳米粒, 并研了其对多环芳烃的比色检测. 结果表明, 磺化杯芳烃修饰的金纳米粒对蒽具有良好的识别选择性. 该比色探针对蒽的检测限可达到2×10-6 mol/L. 这种比色传感器能够实现现场原位检测.     

Novel β-cyclodextrin modified quantum dots as fluorescent probes for polycyclic aromatic hydrocarbons （PAHs）

Water-soluble CdSe/ZnS quantum dots （QDs） were prepared via a simple sonochemical procedure using β-cyclodextrin （CD） as surface coating agent. The QDs displayed a sensitive emission enhancement for anthracene over other related polycyclic aromatic hydrocarbons, and the detection limit was around 1.6 × 10^-8 mol/L.     

Preparation of PDMS-coated microspheres by sol-gel method for sorptive extraction of PAHs

In this paper, a novel SPME mode, PDMS-coated solid glass microspheres （SGMs）, were prepared by sol-gel method. Using homemade thermal desorption unit coupled with CGC-FID, six PAHs as model analytes, the performance of the new mode was characterized. The new extractive phase exhibited high thermal stability and satisfactory extraction capability. The detection limits were 0.01-0.045 ng/mL, and the linearity was from 0.5 ng/mL to 96 ng/mL. The R.S.D.s of repeatability for retention time and peak area were all within 0.074% and 6.7%, respectively. The recoveries of the PAHs were 78-127% from the samples taken from river water.     

Novel β-cyclodextrin modified quantum dots as fluorescent probes for polycyclic aromatic hydrocarbons (PAHs)

Water-soluble CdSe/ZnS quantum dots (QDs)were prepared via a simple sonochemical procedure using β-cyclodextrin (CD)as surface coating agent.The QDs displayed a sensitive emission enhancement for anthracene over other related polycyclic aromatic hydrocarbons,and the detection limit was around 1.6 × 10-8 mol/L.     

有机脱模剂中多环芳烃的高效液相色谱测定

建立了有机硅类和金属皂类脱模剂中多环芳烃的高效液相色谱测定方法。方法所用色谱柱为多聚C18(LC-PAH)柱,流动相为乙腈/水,采用梯度淋洗方式,开始时为体积分数40%乙腈,28min后变为82%乙腈,48min后变成100%乙腈,保持8min。方法的线性范围为0.10~200mg/L,线性相关系数为0.9993~1.0000,平均回收率分别为68.55%~101.2%(有机硅类)和75.29%~99.89%(金属皂类),精密度RSD分别为1.6%~8.1%(有机硅类)和1.8%~6.8%(金属皂类),检出限(S/N=3)分别为0.05~0.10mg/L(有机硅类)和0.05~0.20mg/L(金属皂类)。该方法可以满足有机硅类和金属皂类脱模剂中多环芳烃的检测要求。     

Alkaline extraction in combination with microwave-assisted extraction followed by solid-phase extraction treatment for polycyclic aromatic hydrocarbons in a sediment sample

Microwave-assisted extraction using 1 M KOH/methanol (alkaline-MAE) in combination with solid-phase extraction treatment was developed and applied to polycyclic aromatic hydrocarbons (PAHs) in a sediment sample. Although various conditions were examined (100 or 150 °C for 10 or 30 min), comparable concentrations of PAHs to those obtained by conventional extraction with 1 M KOH/methanol at 70 °C for 4 h were obtained, even at 100 °C for 10 min. The concentrations obtained by using MeOH at 150 °C for 30 min without KOH were lower (by 1.3-37%) than those obtained by alkaline-MAE at 150 °C for 30 min. Since the developed technique can introduce higher concentration of benzo[ghi]perylene relative to those using pressurized liquid extraction (toluene, 150 °C, 15 MPa, 10 min, two cycles), the developed alkaline-MAE is a effective technique.     

New strategies to screen for endocrine-disrupting chemicals in the Portuguese marine environment utilizing large volume injection–capillary gas chromatography–mass spectrometry combined with retention time locking libraries (LVI–GC–MS–RTL)

A new analytical strategy to screen for endocrine-disrupting chemicals (EDCs) in environmental matrices is presented. The strategy uses solid-phase extraction followed by large volume injection and capillary gas chromatography coupled to mass spectrometry combined with retention time locking libraries (SPE-LVI-GC-MS-RTL). Characterization of the proposed methodology (SPE-LVI-GC-MS) for selected classes of EDCs enabled high reproducibility and robustness at the ultratrace level. The RTL databases used allowed hundreds of non-target semivolatiles (i.e., pesticides, polycyclic aromatic hydrocarbons, polychlorinated biphenyls and other classes of suspected EDCs from a great number of unknown environmental matrices) to be simultaneously screened for in an easy, fast and remarkable manner. The application of the proposed methodology to real environmental samples demonstrated its remarkable selectivity and sensitivity at the ultratrace level. Screening assessments performed on water and sediment matrices from eight Portuguese estuaries and coastal waters identified EDC "hotspots." These EDCs mainly come from agricultural and a wide variety of industrial sources, and include pesticides and pesticide metabolites, phenolic derivatives and polycyclic aromatic hydrocarbons, which are included in the lists of priority substances published by international environmental agencies. The estuaries that contained relatively high levels of pesticides were Guadiana, Sado and Mondego, while Minho, Douro and Formosa showed enhanced levels of phenolic derivatives. Dibutyltin and tributyltin, selected as target compounds to be monitored by SPE-LVI-GC-MS in the selected ion monitoring mode, were shown to be widespread contaminants at trace levels in almost all of the sediment matrices assessed. The reliability of the proposed methodology undoubtedly makes it a valuable tool that could replace other analytical strategies currently used to screen for EDCs present in the environment at ultratrace levels.