Determination of oxygen and nitrogen derivatives of polycyclic aromatic hydrocarbons in fractions of asphalt mixtures using liquid chromatography coupled to mass spectrometry with atmospheric pressure chemical ionization

Liquid chromatography coupled to mass spectrometry with atmospheric pressure chemical ionization was used for the determination of polycyclic aromatic hydrocarbon derivatives, the oxygenated polycyclic aromatic hydrocarbons and nitrated polycyclic aromatic hydrocarbons, formed in asphalt fractions. Two different methods have been developed for the determination of five oxygenated and seven nitrated polycyclic aromatic hydrocarbons that are characterized by having two or more condensed aromatic rings and present mutagenic and carcinogenic properties. The parameters of the atmospheric pressure chemical ionization interface were optimized to obtain the highest possible sensitivity for all compounds. The detection limits of the methods ranged from 0.1 to 57.3 μg/L for nitrated and from 0.1 to 6.6 μg/L for oxygenated derivatives. The limits of quantification were in the range of 4.6–191 μg/L for nitrated and 0.3–8.9 μg/L for oxygenated derivatives. The methods were validated against a diesel particulate extract standard reference material (National Institute of Standards and Technology SRM 1975), and the obtained concentrations (two nitrated derivatives) agreed with the certified values. The methods were applied in the analysis of asphalt samples after their fractionation into asphaltenes and maltenes, according to American Society for Testing and Material D4124, where the maltenic fraction was further separated into its basic, acidic, and neutral parts following the method of Green. Only two nitrated derivatives were found in the asphalt sample, quinoline and 2‐nitrofluorene, with concentrations of 9.26 and 2146 mg/kg, respectively, whereas no oxygenated derivatives were detected.     

Determination of oxygenated polycyclic aromatic hydrocarbons in atmospheric aerosol samples by liquid chromatography-tandem mass spectrometry

In this paper, the development of an analytical method using liquid chromatography-tandem mass spectrometry (LC-MS-MS) with atmospheric pressure chemical ionization (APCI) for the determination of 17 oxygenated polycyclic aromatic hydrocarbons (OPAH) is described. These OPAH include ketones, pyrones and diketones. The APCI interface parameters have been optimized for maximum sensitivity. Positive ion mode was proved to be most sensitive for ketones and pyrones while negative ion mode gave better detection limits for target diketones. The detection limits of the method ranged from less than 1.20microg L(-1) for several OPAH solutions (between 0.10 and 0.70microg L(-1) for positive mode and between of 0.19 and 1.20microg L(-1) for negative mode). The analytical method was applied particulate matter (PM(2.5)) samples collected over 24-48h periods between March 2005 and June 2005 in Tempe (Arizona, USA). Before analysis aerosol samples were solvent extracted and concentrated to a final volume of 1mL of methanol. OPAH concentrations observed for this urban site ranged from 0.22 to 3.60ngm(-3).     

Determination of organic pollutants in coking wastewater by dispersive liquid–liquid microextraction/GC/MS

A method based on dispersive liquid–liquid microextraction coupled with GC/MS was developed for quantitative analysis of the major organic pollutants listed in the United States Environmental Protection Agency method 8270 and the 15 European‐priority polycyclic aromatic hydrocarbons in coking wastewater. The major parameters such as extraction solvent, dispersive solvent, solution pH, and extraction time were systematically optimized. The optimum extraction conditions were found to be: 15 μL mixture of 2:1 v/v carbon tetrachloride and chlorobenzene as the extraction solvent, 0.75 mL ACN as the dispersive solvent, solution pH of 8, and extraction time of 2 min. For the major pollutants listed in the United States Environmental Protection Agency 8270, the linear ranges were 0.1 to 100 mg/L, the enrichment factors ranged from 452 to 685, and the relative recoveries ranged from 67.5 to 103.5% with RSDs of 4.0–9.1% (n = 5) at the concentrations of 10 mg/L under the optimum extraction conditions. For the 15 polycyclic aromatic hydrocarbons, the linear ranges were 0.1 to 100 μg/L, the enrichment factors ranged from 645 to 723, and the relative recoveries ranged from 94.5 to 107.6% with RSDs of 4.6–9.0% (n = 5) at the concentrations of 10 μg/L. The usefulness of the developed method was demonstrated by applying it in the analysis of real‐world coking wastewater samples.     

Carbonized cotton fibers via a facile method for highly sensitive solid‐phase microextraction of polycyclic aromatic hydrocarbons

Cotton fiber is an environmentally friendly and natural material with a certain extraction capacity, while its enrichment ability is poor. In order to improve the extraction efficiency of cotton fibers, it was carbonized to form a layer of amorphous carbon as the sorbent by a simple carbonization method. Carbonized cotton fibers were filled into a polyetheretherketone tube for in‐tube solid‐phase microextraction. The carbonization time was investigated to obtain high extraction efficiency. Coupled to high‐performance liquid chromatography, the extraction tube was evaluated with polycyclic aromatic hydrocarbons, estrogens and phthalates, and it exhibited best extraction efficiency for polycyclic aromatic hydrocarbons. Under the optimum conditions, an online analysis method for several polycyclic aromatic hydrocarbons was established with large linear ranges (0.016–0.20 μg/L), low limits of detection (0.005–0.020 μg/L), and high enrichment factors (948–2874). Analysis method was successfully applied to the detection of targets in the real samples and shown satisfactory durability and chemical stability. Moreover, the relative recoveries ranged from 82 to 119.2%, which demonstrated the applicability of carbonized cotton fibers in sample preparation. Compared with other reported methods, the proposed method provided shorter extraction time, higher enrichment factors, comparable limits of detection, and recoveries.     

Determination of polycyclic aromatic hydrocarbons in sediment by liquid chromatography-atmospheric pressure photoionization-mass spectrometry.

We describe a method for the simultaneous determination of 12 kinds of polycyclic aromatic hydrocarbons (PAHs) in sediment based on liquid chromatography-atmospheric pressure photoionization-mass spectrometry (LC/APPI/MS). The method consists of PAH extractions by ultrasonics, clean-up by a solid-phase extraction procedure and determination by LC/APPI/MS. The limits of the determination for PAHs in sediment using the proposed method ranged from 0.06 to 0.9 mg/kg. PAHs were detected by this method in sediment samples on the mg/kg level.     

Determination of polycyclic aromatic hydrocarbons in coastal sediments from the Porto region (Portugal) by microwave-assisted extraction, followed by SPME and GC-MS

A simple low-cost, analytical method based on microwave-assisted extraction of sediments, followed by solid phase micro-extraction and gas chromatography mass spectrometry, was developed and validated for the quantification of sixteen polycyclic aromatic hydrocarbons (PAHs) in marine and estuarine sediment samples. The PAHs were those included in the United States Environmental Protection Agency (US EPA) priority list. Method detection limits were between 0.07 and 0.76 μg/kg dry weight (dw), which makes the current method suitable for environmental analysis. Sediments screened for PAHs from the Douro River estuary and the Porto seacoast exhibit total concentrations that ranged from 58.98 to 156.45 μg/kg dw, and from 51.98 to 54.79 μg/kg dw, respectively. The presence of almost all human carcinogenic PAHs in the analyzed areas indicate that these sediments can be considered polluted, suggesting that future monitoring programs together with an effective coastal management program must be implemented to guarantee the safe usage of the current areas for fishing and bathing.     

分散液液微萃取-气相色谱/质谱法测定水中多环芳烃

用分散液液微萃取-气相色谱/质谱法测定水样中的16种多环芳烃(PAHs)。通过实验确定最佳萃取条件为:20μL四氯化碳作萃取剂,1.0 mL乙腈作分散剂,超声萃取1 min。在优化条件下,多环芳烃的富集倍数达到216～511,方法在0.05～50μg/L范围内呈良好的线性关系,相关系数(R2)在0.9873～0.9983之间,检出限为0.0020～0.14μg/L。相对标准偏差(RSD)在3.82%～12.45%(n=6)之间。该方法成功用于实际水样中痕量多环芳烃的测定。     

In-source fragmentation of partially oxidized mono- and polycyclic aromatic hydrocarbons in atmospheric pressure chemical ionization mass spectrometry coupled to liquid chromatography

Partially oxidized derivatives of polycyclic aromatic hydrocarbons (PAHs) are known to be important environmental pollutants. For the identification of these substances in complex mixtures, e.g. atmospheric aerosol samples, liquid chromatography/mass spectrometry with atmospheric pressure chemical ionization (LC/APCI-MS) has been found to be a suitable analytical technique. In this study 31 derivatives of mono- and polycyclic aromatic hydrocarbons with up to five condensed aromatic rings carrying different functional groups (carboxyl, dicarboxylic anhydride, lactone, hydroxyl, and carbonyl) were characterized by LC/APCI-MS. Each substance was measured in positive and negative ion detection mode at four different fragmentor voltages (90 to 190 V). For the first time, the results show that characteristic and well-interpretable fragmentation patterns can be obtained for these classes of compounds by in-source collision-induced dissociation in a single quadrupole LC/APCI-MS system. For each class of compounds typical spectral features and optimum measurement conditions are reported, and fragmentation pathways are proposed. The study demonstrates the applicability of LC/APCI-MS for the determination of most of the investigated compounds at trace levels, and it provides a database for the identification of unknown partially oxidized aromatic hydrocarbons. Copyright 1999 John Wiley & Sons, Ltd.     

加速溶剂萃取-固相萃取/超高效液相色谱-串联质谱法测定育苗基质中矮壮素与助状素

研究建立了一种加速溶剂萃取-固相萃取/超高效液相色谱-串联质谱法（SPE-UPLC-MS/MS）测定育苗基质中矮壮素和助状素的分析方法。样品采用快速溶剂萃取仪（ASE）提取,经CBA弱阳离子交换柱净化后,在亲水作用色谱柱上用SeQuant ZLC-HILIC MEKCK色谱柱进行分离;电喷雾正离子（ESI+）模式电离,多反应监测（MRM）模式检测。矮壮素和助状素的质量浓度在0.2~10 μg/kg范围内线性关系良好（r2>0999）,在2、5、10 μg/kg加标水平的平均回收率分别为77%~106%和97%~111%,相对标准偏差（RSD）分别为7.3%~21.7%和5.6%~16.1%,检出限（LOD）均为0.02 μg/kg,定量下限（LOQ）均为0.1 μg/kg。该方法简便、快速、灵敏、准确,适合育苗基质中矮壮素和助状素残留的确证和定量测定。     

Atmospheric-pressure laser ionization: a novel ionization method for liquid chromatography/mass spectrometry

We report on the development of a new laser-ionization (LI) source operating at atmospheric pressure (AP) for liquid chromatography/mass spectrometry (LC/MS) applications. APLI is introduced as a powerful addition to existing AP ionization techniques, in particular atmospheric-pressure chemical ionization (APCI), electrospray ionization (ESI), and atmospheric pressure photoionization (APPI). Replacing the one-step VUV approach in APPI with step-wise two-photon ionization strongly enhances the selectivity of the ionization process. Furthermore, the photon flux during an ionization event is drastically increased over that of APPI, leading to very low detection limits. In addition, the APLI mechanism generally operates primarily directly on the analyte. This allows for very efficient ionization even of non-polar compounds such as polycyclic aromatic hydrocarbons (PAHs). The APLI source was characterized with a MicroMass Q-Tof Ultima II analyzer. Both the effluent of an HPLC column containing a number of PAHs (benzo[a]pyrene, fluoranthene, anthracene, fluorene) and samples from direct syringe injection were analyzed with respect to selectivity and sensitivity of the overall system. The liquid phase was vaporized by a conventional APCI inlet (AP probe) with the corona needle removed. Ionization was performed through selective resonance-enhanced multi-photon ionization schemes using a high-repetition-rate fixed-frequency excimer laser operating at 248 nm. Detection limits well within the low-fmol regime are readily obtained for various aromatic hydrocarbons that exhibit long-lived electronic states at the energy level of the first photon. Only molecular ions are generated at the low laser fluxes employed ( approximately 1 MW/cm(2)). The design and performance of the laser-ionization source are presented along with results of the analysis of aromatic hydrocarbons.     

三苄基杯[6]芳烃固相微萃取复合涂层的研制及其应用

采用溶胶-凝胶方法制备了三苄基杯[6]芳烃/羟基硅油(C[6]/OH-TSO)固相微萃取(SPME)探头, 通过对多环芳烃和酞酸酯(PAEs)的分析考察了新型C[6]/OH-TSO探头的性能. 结果表明: 杯[6]芳烃SPME探头对这些非极性和弱极性的芳香化合物有很好的萃取效果和选择性, 具有耐高温、使用寿命长等特点. 建立了SPME与气相色谱-氢火焰(GC-FID)联用测定化妆品中PAEs的方法. 该方法检测限低, 重现性好(RSD＜9%), 线性范围宽(2～3个数量级). 回收率在83.42%～98.85%之间.     

High-performance liquid chromatography coupled to direct analysis in real time mass spectrometry: investigations on gradient elution and influence of complex matrices on signal intensities

Direct analysis in real time (DART) time-of-flight mass spectrometry (TOF-MS) has been tested for its suitability as a detector for gradient elution HPLC. Thereby a strong dependency of signal intensity on the amount of organic solvent present in the eluent could be observed. Adding a make-up liquid (iso-propanol) post-column to the HPLC effluent greatly enhanced detection limits for early eluting compounds. Limits of detection achieved employing this approach were in the range of 7-27 μg L(-1) for the parabene test mixture and 15-87 μg L(-1) for the pharmaceuticals. In further investigations DART ionization was compared to several other widely used atmospheric pressure ionization methods with respect to signal suppression phenomena occurring in when samples with problematic matrices are analyzed. For this purpose extracts from environmental and waste water samples were selected as model matrices which were subsequently spiked with a set of six substances commonly present in personal care products as well as six pharmaceuticals at concentration levels between 100 μg L(-1) and 500 μg L(-1) corresponding to 100 ng L(-1) and 500 ng L(-1) respectively in the original sample. With ionization suppression of less than 11% for most analytes investigated, DART ionization showed similar to even somewhat superior behavior compared to atmospheric pressure chemical ionization (APCI) and atmospheric pressure photo ionization (APPI) for the Danube river water extract; for the more challenging matrix of the sewage plant effluent extract DART provided better results with ion suppression being less than 11% for 9 out of 12 analytes while values for APCI were lying between 20% and >90%. Electrospray ionization (ESI) was much more affected by suppression effects than DART with values between 26% and 80% for Danube river water; in combination with the sewage plant effluent matrix suppression >50% was observed for all analytes.     

Determination of lincomycin and tylosin residues in honey using solid-phase extraction and liquid chromatography-atmospheric pressure chemical ionization mass spectrometry

An analytical method for the determination of residues of the antibiotic drugs lincomycin and tylosin in honey was developed. The procedure employed a solid-phase extraction for the isolation of lincomycin and tylosin from diluted honey samples. The antibiotic residues were subsequently analyzed by reversed-phase HPLC with atmospheric pressure chemical ionization mass spectrometric detection. Average analyte recoveries for lincomycin and tylosin ranged from 84 to 107% in replicate sets of honey samples fortified with drug concentrations of 0.01, 0.5, and 10 microg/g. The method detection limits were determined to be 0.007 and 0.01 microg/g for lincomycin and tylosin, respectively.     

Determination of polycyclic aromatic hydrocarbons in soy isoflavone nutraceutical products by gas chromatography coupled to triple quadrupole tandem mass spectrometry

Thirteen polycyclic aromatic hydrocarbons have been determined in soy‐based nutraceutical products. First, an optimization of extraction procedure was performed, and a solid–liquid extraction assisted by sonication and a dilute and shoot procedure were compared, selecting the dilute and shoot approach for the extraction of target compounds, utilizing a mixture of acetone/n‐hexane (1:1 v/v) as extractant solvent. After this, a clean‐up step was needed bearing in mind the complexity of these matrices. Dispersive solid‐phase extraction, using a mixture of C₁₈ and Zr‐Sep+ (25 mg/mL each) was used. The separation was achieved by gas chromatography and detection with triple quadrupole tandem mass spectrometry. For quantification purposes, matrix‐matched calibration was used. The validation was applied at three concentration levels (20, 100 and 250 μg/kg), obtaining recoveries between 70 and 120% and precision values equal to or lower than 23%. Limits of detection and quantification were below 8 and 20 μg/kg, respectively. The method was applied in 11 samples, detecting five polycyclic aromatic hydrocarbons at concentrations ranging from 4.1 to 18.5 μg/kg.     

Simultaneous determination by ultra-performance liquid chromatography–atmospheric pressure chemical ionization time-of-flight mass spectrometry of nitrated and oxygenated PAHs found in air and soot particles

An ultra-performance liquid chromatographic-atmospheric pressure chemical ionization time-of-flight mass spectrometric (UPLC-APCIToFMS) method for rapid analysis of twelve nitrated polycyclic aromatic hydrocarbons (NPAHs) and nine oxygenated polycyclic aromatic hydrocarbons (OPAHs) in particle samples has been developed. The extraction step using pressurized liquid extraction was optimized by experimental design methods and the concentrated extracts were analyzed without further clean-up. Matrix effects resulting in suppression or enhancement of the response during the ionization step were not observed. The suitability of the developed method is demonstrated by analysis of six different particle samples including standard reference materials, atmospheric particles collected by a high-volume sampler at an urban background site, and a soot sample from a burner. Results from these measurements showed clear differences between the different kinds of samples. Concentrations from reference materials are in good agreement with those from previous studies. Additionally a clear seasonal trend could be observed in atmospheric NPAH and OPAH concentrations found in real samples, with higher concentrations in winter.     

Sensitive method for the determination of nitrated polycyclic aromatic hydrocarbons in the human diet

The presence of nitrated polycyclic aromatic hydrocarbons (nitro-PAHs) as contaminants in foods is nowadays a legitimate cause of concern, as they are reported to be strong direct-acting mutagens and carcinogens that may pose a risk to human health. Nevertheless, their concentrations in foods are in the ultra-trace region. In this study, we present a very sensitive analytical method for the determination of this compound class in complex food matrices. Special emphasis was put on sample extraction and clean up. Recoveries of 75% could be obtained for 1- and 2-nitronaphthalene; for all other compounds investigated the recoveries were >/=94%. The determination of the compounds was performed by gas chromatography-mass spectrometry. The results show that the use of negative chemical ionization (NCI) increases the sensitivity by one order of magnitude in comparison to electron impact ionization (EI) (limits of detection 0.07-0.25 micro g kg(-1) for EI and 0.01-0.02 micro g kg(-1) for NCI). The influence of the sample matrix on the sensitivity of the method is demonstrated with extracts of a sample from a duplicate diet study. Due to the lack of a certified reference material the suitability of the method is demonstrated with pumpkin seed oil that was spiked with nitro-PAHs at two different concentration levels.     

改进QuEChERS-气相色谱-质谱法快速分析测定农用土壤中多环芳烃

建立农用土壤中16种多环芳烃的改进QuEChERS快速提取净化方法及气相色谱-质谱检测方法,并通过对西安市周边农用土壤样品的分析,调查土壤中多环芳烃的污染情况.土壤样品用KOH饱和的甲醇碱化处理后,用丙酮-正已烷(1+1)为提取溶剂,涡旋混匀后超声提取,提取液按改进QuEChERS方法加入无水MgSO4、硅胶及正丙基乙二胺(PSA)进行净化,检测时选用DB -5 MS(30m×0.25 mm×0.25 μm)色谱柱分离,EI电离源及离子监测模式检测,16种多环芳烃的测定低限0.7～3.2μg/kg,加标回收率79.8％ ～ 109.6％,相对标准偏差均低于9.4％.检测的农用土壤样品中均检出有不同程度的多环芳烃残留,约16.7％的土壤样品为轻度污染.     

Determination of polycyclic aromatic hydrocarbons in water by gas chromatography/mass spectrometry with accelerated sample preparation

A novel simplified sample preparation method for quantitative analysis of polycyclic aromatic hydrocarbons (PAH) in water samples by gas chromatography/mass spectrometry (GC/MS) was proposed. The method requires just 1 mL of water and 1 mL of dichloromethane. The detection limits of PAH with the use of high resolution GC/MS are about 1 μg/Λ, while the limits of quantification—10 μg/L. These limits correspond to those for the standard 8270 method of the United States Environmental Protection Agency.     

Glycidyl fatty acid esters in food by LC-MS/MS: method development

An improved method based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the analysis of glycidyl fatty acid esters in oils was developed. The method incorporates stable isotope dilution analysis (SIDA) for quantifying the five target analytes: glycidyl esters of palmitic (C16:0), stearic (C18:0), oleic (C18:1), linoleic (C18:2) and linolenic acid (C18:3). For the analysis, 10 mg sample of edible oil or fat is dissolved in acetone, spiked with deuterium labelled analogs of glycidyl esters and purified by a two-step chromatography on C18 and normal silica solid phase extraction (SPE) cartridges using methanol and 5% ethyl acetate in hexane, respectively. If the concentration of analytes is expected to be below 0.5 mg/kg, 0.5 g sample of oil is pre-concentrated first using a silica column. The dried final extract is re-dissolved in 250 μL of a mixture of methanol/isopropanol (1:1, v/v), 15 μL is injected on the analytical C18 LC column and analytes are eluted with 100% methanol. Detection of target glycidyl fatty acid esters is accomplished by LC-MS/MS using positive ion atmospheric pressure chemical ionization operating in Multiple Reaction Monitoring mode monitoring 2 ion transitions for each analyte. The method was tested on replicates of a virgin olive oil which was free of glycidyl esters. The method detection limit was calculated to be in the range of 70-150 μg/kg for each analyte using 10 mg sample and 1-3 μg/kg using 0.5 g sample of oil. Average recoveries of 5 glycidyl esters spiked at 10, 1 and 0.1 mg/kg were in the range 84% to 108%. The major advantage of our method is use of SIDA for all analytes using commercially available internal standards and detection limits that are lower by a factor of 5-10 from published methods when 0.5 g sample of oil is used. Additionally, MS/MS mass chromatograms offer greater specificity than liquid chromatography-mass spectrometry operated in selected ion monitoring mode. The method will be applied to the survey of glycidyl fatty acid esters in food products on the Canadian market.     

Simultaneous determination of 16 polycyclic aromatic hydrocarbons in reclaimed water using solid‐phase extraction followed by ultra‐performance convergence chromatography with photodiode array detection

A new fast and effective analysis method has been developed to simultaneously determine 16 polycyclic aromatic hydrocarbons in reclaimed water samples by ultra‐performance convergence chromatography with photodiode array detection and solid‐phase extraction. The parameters of ultra‐performance convergence chromatography on the separation behaviors and the crucial condition of solid‐phase extraction were investigated systematically. Under optimal conditions, the 16 polycyclic aromatic hydrocarbons could be separated within 4 min. The limits of detection and quantification were in the range of 0.4–4 and 1–10 μg/L in water, respectively. This approach has been applied to a real industrial wastewater treatment plant successfully. The results showed that polycyclic aromatic hydrocarbons were dramatically decreased after chemical treatment procedure, and the oxidation procedure was effective to remove trace polycyclic aromatic hydrocarbons.