Identification and quantitative analysis of nitrogen-containing polycyclic aromatic hydrocarbons in sediments

An integrated analytical methodology has been developed for determining nitrogen-containing polycyclic aromatic hydrocarbons, which enables quantitation of individual contaminants as low as 1 μg/kg in sediment samples. A cross-sectional profile from the Hamilton Harbour sediment samples was analyzed for azaarenes. These contaminants were separated by Soxhlet extraction, and pH adjustment allowed their isolation from different classes of neutral and acidic components. Separation and identification of the organic bases in each sample were achieved by using open tubular column gas chromatography with thermionic detection and HRGC-mass spectrometry. Organic bases present in the samples included mostly azaarenes such as acridines, benzacridines, azafluorene, benzoquinolines, azapyrenes, etc. Quantitation and environmental significance of these compounds are discussed. Recoveries of individual azaarenes at two different levels were evaluated. Data presented indicate that detection limits of this method are between 1 and 10 μg/kg. Recovery azaarenes from bottom sediment samples at concentration levels between 1 to 100 μg/kg is 81 ± 17%.     

固相萃取/气相色谱-质谱法测定玩具中10种有机物的迁移量

建立了玩具中10种有机物迁移量的固相萃取/气相色谱-质谱测定方法。样品在25 mL去离子水中迁移60min,得到的迁移液流经Chromabond Easy固相萃取柱,用乙酸乙酯洗脱5次,每次1 mL。洗脱液过滤膜后通过60m DB-624色谱柱分离,质谱进行检测,外标法定量。方法对于不同有机物的定量限(LOQ)在0.0...     

Determination of basic azaarenes and polynuclear aromatic hydrocarbons in airborne particulate matter by gas chromatography

Polynuclear aromatic hydrocarbons (PAH) and their nitrogen analogs, basic azaarenes, are extracted from samples of airborne particulate matter by toluene with ultrasonic treatment. The basic azaarenes are extracted from the toluene phase with phosphoric acid, re-extracted from the phosphoric acid phase (adjusted to pH 14 with potassium hydroxide) with dichloromethane, and determined by capillary gas chromatography (g.c.) with a nitrogen-sensitive detector. The PAH in the toluene phase are isolated by means of semipreparative high-performance liquid chromatography and liquid-liquid extraction and determined by g.c. with a flame-ionization detector. Eleven basic azaarenes were identified; their concentration were one to two orders of magnitude lower than those of PAH. Results from the determination of the concentrations of basic azaarenes and PAH in the atmosphere in a busy street and in a suburban residential area of Copenhagen are presented and discussed.     

热脱附-气相色谱-质谱法应用于工业源废气中挥发性有机物的目标和非目标筛查

建立了固相吸附热脱附-气相色谱-质谱(TD-GC-MS)综合筛查工业源废气中挥发性有机物(VOCs)的方法。对两种型号的固相吸附管进行了比较,最终选择使用Tenax SS TD Tubes吸附管。气体样品以恒定流速通过吸附管,富集分析物,经热脱附后,用GC-MS进行检测,目标化合物以内标法定量,非目标化合物的含量以甲苯的响应系数计算。方法检出限为1.06~5.44 ng,以采样体积300 mL计算,目标化合物的检出限为0.004~0.018 mg/m~3。吸附管平均加标回收率为78.4%~89.4%,相对标准偏差为3.9%~14.4%(n=7)。应用该方法对大连市某垃圾焚烧发电厂排放的废气进行VOCs目标及非目标化合物综合筛查,共检出29种VOCs,其中仅5种VOCs为预先设定的目标化合物,另外24种为非目标化合物,5种目标化合物含量仅占所有检出物总量的26.7%。证明了工业源废气VOCs分析中非目标化合物筛查的重要性,该研究思路对完整测定工业源挥发性有机污染物分布具有一定的借鉴意义。     

Phosphite‐Catalyzed C−H Allylation of Azaarenes via an Enantioselective [2,3]‐Aza‐Wittig Rearrangement

A phosphite‐mediated [2,3]‐aza‐Wittig rearrangement has been developed for the regio‐ and enantioselective allylic alkylation of six‐membered heteroaromatic compounds (azaarenes). The nucleophilic phosphite adducts of N‐allyl salts undergo a stereoselective base‐mediated aza‐Wittig rearrangement and dissociation of the chiral phosphite for overall C?H functionalization of azaarenes. This method provides efficient access to tertiary and quaternary chiral centers in isoquinoline, quinoline, and pyridine systems, tolerating a broad variety of substituents on both the allyl part and azaarenes. Catalysis with chiral phosphites is also demonstrated with synthetically useful yields and enantioselectivities.     

High-performance liquid chromatographic determination of azaarenes and their metabolites in groundwater affected by creosote wood preservatives

Polynuclear azaheterocyclic compounds (azaarenes) are nitrogen-containing analogs of polycyclic aromatic hydrocarbons (PAHs). The nitrogen atom in the ring system causes these compounds to be slightly polar and considerably more water soluble than related PAHs. A method using a solid-surface sorption technique to extract and concentrate azaarenes and their principle metabolites present in groundwater that contains creosote waste is described. Analyte isolation and concentration is accomplished by solid-phase extraction on n-octadecyl cartridges followed by instrumental determination involving high-performance liquid chromatography. Separations and detection are achieved using flexible-walled, wide-bore columns with ultraviolet and fluorescence photometric detectors connected in series. Fluorescence detection alone is insufficient because the fluorescence response produced by two-ring azaarenes is limited. Short wavelength (229 nm) absorbance detection provides improved sensitivity for these compounds and peak rationing for more definitive identification. In this study, oxygen-containing metabolites of quinoline, isoquinoline, and acridine are detected in groundwater from hazardous waste sites in Pensacola, Florida and St. Louis Park, Minnesota. Concentrations ranging from mg/L to ng/L are measured. The dependence of measured octanol-water partition coefficients on pH is discussed in the context of the isolation chemistry. As a direct bacterial degradation product of acridine with a relatively long environmental persistence, 9-acridinone may serve as a biogenic marker signaling creosote contamination of groundwater.     

On-line characterization of gaseous and particulate organic analytes using atmospheric pressure chemical ionization mass spectrometry

A modified atmospheric pressure chemical ionization ion source is applied for direct analysis of volatile or low volatile organic compounds in air. The method is based on the direct introduction of the analytes in the gas phase and/or particle phase into the ion source of a commercial ion-trap mass spectrometer. Two methods are employed for the production of primary ions at atmospheric pressure, photoionization and corona discharge. It is shown that in the presence of a dopant, photoionization can be a highly efficient ionization method also for real-time analysis with detection limits for selected analytes in the lower ppt-range. Using corona discharge for the production of primary ions, which is instrumentally easier since no additional chemicals have to be added to the sample flow, we demonstrate the analytical potential of on-line atmospheric pressure chemical ionization mass spectrometry for reaction monitoring experiments. To do so, an atmospherically relevant gas phase reaction is carried out in a 500 l reaction chamber and gaseous and particulate compounds are monitored in the positive and negative ion mode of the mass spectrometer.     

Development of a method for simultaneous analysis of PCDDs, PCDFs, PCBs, PBDEs, PCNs and PAHs in Antarctic air

The development of a unique analytical method for the determination of five classes of persistent organic pollutants (POPs) in atmospheric gas and the particle phase through gas chromatography coupled to high-resolution mass spectrometry is presented. Every step of the pre-analytical and analytical optimization process is described. Great effort was put into simplifying the traditional techniques, with reference to EPA and literature methods. Automated instruments were used for sample extraction and cleanup in order to enhance repeatability and reduce contamination risks. Unlike most common approaches, no separation of the analytes was performed before the GC analysis in order to avoid sample fractionation and to save time and materials. This allowed low instrumental and method detection limits (pg to sub-pg) to be achieved. Accuracy and precision were tested by fortifying the matrix and analysing standard reference materials (NIST SRM 1649b Urban Dust and 2585 Organic Contaminants in House Dust). The method was applied to five samples from Terra Nova Bay, Antarctica. Concentrations of polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs), polychlorinated biphenyls (PCBs), polychlorinated naphthalenes (PCNs), polybrominated diphenyl ethers (PBDEs) and polycyclic aromatic hydrocarbons (PAHs) are presented. Lighter compounds dominate the distribution and are mainly present in the gaseous phase. The observed pattern may be attributable to long-range transport. Results are in general agreement with literature data, where available.     

Development of an analytical method based on microwave-assisted extraction and solid phase extraction cleanup for the determination of organochlorine pesticides in animal feed

A method to determine 21 organochlorine pesticides in animal feed samples using microwave assisted extraction and solid phase extraction cleanup was optimised regarding its main parameters. After extraction with hexane-acetone (50:50), three different sorbents (alumina/ENVI-Florisil, ENVI-Carb and ENVI-Carb II/PSA) were assayed for the cleanup step. Analytes were eluted with hexane-ethyl acetate (80:20) and determined by gas chromatography and electron capture detection followed by gas chromatography-mass spectrometry. ENVI-Carb and ENVI-Carb II/PSA provided colourless eluates but fewer interferent compounds were found in ENVI-Carb II/PSA chromatograms, so this system was selected to carry out the purification of the extracts. The analytical recoveries obtained with this method were close to 100% in most cases with relative standard deviations lower than 10%. These percentages were similar to those obtained with the Soxhlet extraction procedure, which shows the method suitable for the determination of organochlorine pesticides in animal feed material. The method was also validated with the analysis of a certified reference material (CRM-115 BCR), and the results obtained were in good accordance with the certified values.     

A liquid chromatography–atmospheric pressure photoionization tandem mass spectrometric method for the determination of azaarenes in atmospheric particulate matter

The development, optimization and validation of a liquid chromatography–atmospheric pressure photoionization tandem mass spectrometric (LC–APPI/MS/MS) method for the determination of 15 azaarenes (4-azafluorene, benzo[h] and -[f]quinoline, phenanthridine, acridine, 1-azafluoranthene, 4-azapyrene, benz[a]- and -[c]acridine, -10-azabenzo[a]pyrene, 7,9- and 7,10-dimethylbenz[c]acridine, dibenz[a,j]-, -[c,h] and [a,i]acridine) in airborne particulate matter is described. Each compound was detected and quantified operating in multiple reaction monitoring mode. Extraction of azaarenes was achieved using accelerated solvent extraction (ASE) with dichlormethane/methanol (50/50, v/v). After extraction, no additional clean-up procedure like solid phase or liquid/liquid extraction was necessary. Limits of quantification (S/N × 10) ranged from 0.2 pg/μl to 1.4 pg/μl, matrix dependent recoveries were between 57% and 94%, with relative standard deviations from 8% to 17%. Applicability of the method was demonstrated analyzing 10 samples of particulate matter (PM_2.5) collected in winter 2008. In all samples dimethylbenz[c]acridines as well as dibenzacridines were below the limit of quantification, concentration of the remaining analytes were in the range from 0.002 ng/m³ to 0.356 ng/m³.     

Simultaneous analysis of oxygenated and nitrated polycyclic aromatic hydrocarbons on standard reference material 1649a (urban dust) and on natural ambient air samples by gas chromatography-mass spectrometry with negative ion chemical ionisation

This study deals with the development of a routine analytical method using gas chromatography-mass spectrometry with negative ion chemical ionisation (GC/NICI-MS) for the determination of 17 nitrated polycyclic aromatic hydrocarbons (NPAHs) and 9 oxygenated polycyclic aromatic hydrocarbons (OPAHs) present at low concentrations in the atmosphere. This method includes a liquid chromatography purification procedure on solid-phase extraction (SPE) cartridge. Application of this analytical procedure has been performed on standard reference material (SRM 1649a: urban dust), giving results in good agreement with the few data available in the literature. The analytical method was also applied on ambient air samples (on both gas and particulate phases) from the French POVA program (POllution des Vallées Alpines). NPAHs concentrations observed for a rural site during the Winter period are about 0.2-100.0pgm(-3) in the particulate phase and about 0.0-20.0pgm(-3) in the gas phase. OPAHs present concentrations 10-100 times higher (0.1-2.0ngm(-3) and 0.0-1.4ngm(-3) for the particulate and the gas phases, respectively). These preliminary results show a good correlation between the characteristics of the sampling site and the compound origins (primary or secondary).     

Increasing the sensitivity of an LC-MS method for screening material extracts for organic extractables via mobile phase optimization

Organic extractables (substances extracted from materials used in pharmaceutical packaging) are discovered, identified, and quantified via screening of extracts with analytical methods including liquid chromatography with mass spectrometric detection (LC-MS). Because extractables include a large number of diverse compounds that are typically present in plastic extracts at low levels, the LC-MS methods must be broad scope and sensitive. To accomplish these objectives, screening studies typically couple gradient reversed-phase separations with electrospray MS detection (both positive and negative ion modes). While such methods are generally applicable for a number of extractables, they are not optimal for some commonly encountered extractables due to either poor chromatographic performance (e.g., peak tailing) or poor MS response. Modifications to mobile phase composition (e.g., pH adjustment) were examined to improve the performance of an LC-MS screening method. The use of 0.1% acetic acid with 1 mM ammonium acetate (pH 3.6) as the aqueous portion of the mobile phase provided favorable sensitivities for a number of extractables both in positive and negative ion modes. In positive ion mode, the acidic mobile phase improved responses for moderately weak basic compounds by increasing their degree of protonation. For very weak basic compounds such as amides, ammonium ions in the mobile phase promoted proton adduct responses. In negative ion mode, an acidic mobile phase containing acetate anion improved ESI responses for acidic compounds, primarily due to gas phase effects.     

气相色谱-离子阱质谱联用测定玩具中21种致敏性芳香剂

建立了气相色谱-离子阱质谱联用测定布绒、贴纸和塑料玩具中苯甲醇等21种致敏性芳香剂的方法。对于布绒和贴纸玩具样品,采用丙酮超声振荡提取20 min后过0.45 μm滤膜,经HP-1MS色谱柱(50 m×0.2 mm×0.5 μm)分离,离子阱质谱检测。对于塑料玩具样品,采取溶解-沉淀方式提取,经Envi-carb石墨化碳固相萃取小柱净化,旋蒸、氮吹浓缩,过0.45 μm滤膜后进行测定,外标法定量。方法对不同物质的定量限(LOQ)为0.02～40 mg/kg,线性范围为0.002～50 mg/L,低、中、高3个添加水平的平均回收率为82.2%～110.8%,相对标准偏差(RSD)为0.6%～10.5%。该方法准确、灵敏,可用于玩具中苯甲醇等21种致敏性芳香剂含量的检测。     

Speciation of butyltin compounds in marine sediments by preconcentration on C60 and gas chromatography-mass spectrometry

A new method for the speciation of butyltin compounds by solid phase extraction and direct injection using gas chromatography-mass spectrometry (GC/MS) is described. The compounds were complexed with sodium diethyldithiocarbamate and retained on a C60 sorbent column. The neutral chelates of butyltin compounds were eluted with ethyl acetate containing NaBPr4 as derivatising reagent. The main analytical figures of merit of the proposed method for 10 ml of sample are: linear range 0.2-35 ng/g expressed as Sn; limits of detection, 0.07, 0.09 and 0.10 ng/g as Sn for monobutyltin, dibutyltin and tributyltin, respectively. No interferences from metal ions such as Zn2+, Fe3+, Sb3t, Pb2+, Ni2+ and Mn2+ were observed in the determination of organotin compounds. The validation of method was performed out by the analysis of a standard reference sediment (CRM 462). The method was also applied to the determination of butyltin compounds in marine sediment samples.     

Determination of organic compounds from wood combustion aerosol nanoparticles by different gas chromatographic systems and by aerosol mass spectrometry

Organic compounds in atmospheric nanoparticles have an effect on human health and the climate. The determination of these particles is challenged by the difficulty of sampling, the complexity of sample composition, and the trace-level concentrations of the compounds. Meeting the challenge requires the development of sophisticated sampling systems for size-resolved particles and the optimization of sensitive, accurate and simple analytical techniques and methods. A new sampling system is proposed where particles are charged with a bipolar charger and size-segregated with a differential mobility analyzer. This system was successfully used to sample particles from wood pyrolysis with particle sizes 30–100 nm. Particles were analyzed by four techniques: comprehensive two-dimensional gas chromatography–time-of-flight mass spectrometry, gas chromatography–time-of-flight mass spectrometry, gas chromatography–quadrupole mass spectrometry, and aerosol mass spectrometry (aerosol MS). In the chromatographic techniques, particles were collected on a filter and analyzed off-line after sample preparation, whereas in the aerosol MS, particle analysis was performed directly from the particle source. Target compounds of the samples were polyaromatic hydrocarbons and n-alkanes. The analytical techniques were compared and their advantages and disadvantages were evaluated. The sampling system operated well and target compounds were identified in low concentrations.     

Determination of sugar compounds in atmospheric aerosols by liquid chromatography combined with positive electrospray ionization mass spectrometry

We here report a method for the determination of sugar compounds of known presence in atmospheric aerosols using liquid chromatography (LC) combined with positive electrospray ionization mass spectrometry (MS). The target analytes include C(3)-C(6) monosaccharide alcohols (glycerol, erythritol, xylitol, mannitol), C(5)-C(6) monosaccharides (xylose, glucose, and levoglucosan), a disaccharide (sucrose), and a trisaccharide (melezitose). A mobile phase consisting of 20% 10 mM aqueous ammonium acetate, 8% methanol, and 72% water was found to provide abundant [M+NH(4)](+) adduct ions when coupled with electrospray ionization. Use of a polymer-based amino analytical column resolved the target compounds from the bulk solvent and provided limited separation among the target compounds. The target analytes were quantified using their [M+NH(4)](+) ions. Sample pretreatment was greatly simplified in comparison with the more commonly used gas chromatographic methods. It involved extraction of aerosol filters in methanol, evaporation of the solvent, and reconstitution with 5 mM ammonium acetate in water prior to the LC-MS analysis. The analyte recoveries were measured at the levels of 100, 500 and 1000 microg/L to be in the range of 78-102%, 94-112%, and 92-110%, respectively. The detection limits were lower than 10 pmol/injection for the tested target compounds except for xylose. Xylose had a detection limit of 95 pmol/injection. The method was applied to analyze 30 atmospheric aerosol samples to demonstrate its feasibility. The LC-MS method made possible the detection of trisaccharides as aerosol constituents for the first time.     

顶空气相色谱法测定化妆品中15种挥发性有机溶剂残留

建立了化妆品中15种挥发性有机溶剂残留的顶空气相色谱测定方法。样品经60 ℃、30 min静态顶空后,采用气相色谱-氢火焰离子化检测器进行检测,外标法定量。加标回收试验结果表明: 15种挥发性有机溶剂残留平均回收率为62.8%～116%,相对标准偏差均小于5%。方法的检出限为0.09～0.68 mg/kg。该方法可有效克服基体干扰,一次进样可同时分离和测定化妆品中15种挥发性有机溶剂,准确灵敏,简单快速,适用于化妆品中挥发性有机溶剂残留的检测。     

液相色谱串联质谱法测定化妆品中的双酚A、辛基酚及壬基酚

建立了护肤化妆品中双酚A、辛基酚和壬基酚的超高效液相色谱串联质谱分析方法。样品经二氯甲烷提取,氨基固相萃取柱净化后,用甲醇定容,采用Waters UPLC BEH C18色谱柱,以甲醇-0.05%氨水为流动相,梯度洗脱分离后,串联四极杆质谱多反应监测方式检测,以保留时间和子离子比定性,外标法定量。在优化条件下,该方法 5 min内可完成4种待测物的分析。双酚A、辛基酚和壬基酚在0.5～50.0μg/L范围内线性关系良好,相关系数均大于0.999,方法的定量下限(LOQs)均为0.5μg/kg;在加标水平为0.5、1.0、10.0μg/kg时,护肤霜和护肤水样品中4种待测物的平均加标回收率为80%～96%,相对标准偏差(n=6)小于15%。该方法准确、快速、灵敏,适用于护肤化妆品中双酚A、辛基酚和壬基酚的快速确认和定量检测。     

Nano and rapid resolution liquid chromatography–electrospray ionization–time of flight mass spectrometry to identify and quantify phenolic compounds in olive oil

The applicability of nanoLC‐ESI‐TOF MS for the analysis of phenolic compounds in olive oil was studied and compared with a HPLC method. After the injection, the compounds were focused on a short capillary trapping column (100 μm id, effective length 20 mm, 5 μm particle size) and then nanoLC analysis was carried out in a fused silica capillary column (75 μm id, effective length 10 μm, 3 μm particle size) packed with C18 stationary phase. The mobile phase was a mixture of water + 0.5% acetic acid and ACN eluting at 300 nL/min in a gradient mode. Phenolic compounds from different families were identified and quantified. The quality parameters of the nanoLC method (linearity, LODs and LOQs, repeatability) were evaluated and compared with those obtained with HPLC. The new methodology presents better sensitivity (reaching LOD values below 1 ppb) with less consumption of mobile phases, but worse repeatability, especially inter‐day repeatability, resulting in more difficulties to get highly accurate quantification. The results described in this article open up the application fields of this technique to cover a larger variety of compounds and its advantages will make it especially useful for the analysis of samples containing low concentration of phenolic compounds, as for instance, in biological samples.     

A gas chromatography quartz crystal microbalance for speciation of nitroaromatic compounds in landfill gas

A new method based on separation with gas chromatography and detection with a quartz crystal microbalance was used for quantification of nitrobenzene, 2-, 3- and 4-nitrotoluene in landfill gas. The analytical error, the analysis time and general analytical performance were identical for gas chromatography-mass spectrometry (GC-MS) and gas chromatography-quartz crystal microbalance (GC-QCM). GC-QCM constitutes a very inexpensive alternative to GC-MS for monitoring nitroaromatic compounds in landfill gas.