Assaying particle-bound polycyclic aromatic hydrocarbons from archived PM2.5 filters

Airborne particulate matter contains numerous organic species, including several polycyclic aromatic hydrocarbons (PAHs) that are known or suspected carcinogens. Existing methods for measuring airborne PAHs are complex and costly, primarily because they are designed to collect both gas-phase and particle-phase PAH constituents. Here, we report an assay for measuring particle-bound PAHs in archived filters from the network of U.S. monitoring stations for particles less than 2.5 microm in diameter (PM2.5), without the need for deploying specialized samplers. PAHs are extracted from Teflon filters with dichloromethane, concentrated, and measured at trace levels using gas chromatography-mass spectrometry. Although PAHs with 3-6 aromatic rings can be assayed, results are only unambiguously accurate for compounds with 5- or 6-rings, due to variable vaporization losses of the more volatile 3- and 4-ring compounds during sampling and/or storage. The method was evaluated for sensitivity, recovery, precision, and agreement of paired air samples, using PM2.5 samplers locally in Chapel Hill, NC. Additionally, three sets of archived samples were analyzed from a study of PM2.5 in the Czech Republic. Levels of some 4-ring and all 5- and 6-ring PAHs in both the local and Czech samples were consistent with published results from investigations employing PAH-specific air samplers. This work strongly suggests that assessment of particle-bound 5- and 6-ring PAHs from archived PM2.5 filters is quantitatively robust. The assay may also be useful for selected 4-ring compounds, notably chrysene and benzo(a)anthracene, if PM2.5 filters are stored under refrigeration.     

气相色谱-质谱法测定大气颗粒物中的有机胺类物质

建立了大气颗粒物中有机胺类物质的气相色谱-质谱(GC-MS)分析方法.样品用超纯水超声萃取,然后在碱性条件下,用苯磺酰氯(Benzenesulfonyl chloride,BSC)衍生化,衍生物用二氯甲烷萃取,最后用DB-5MS色谱柱分离测定,实现了13种有机胺(包括7种脂肪胺、2种杂环胺和4种芳香胺)的同时测定.本方法的仪器检出限(S/N=3)和定量限(S/N=10)分别为0.00008～0.017 μg/mL和0.00026～0.0565 μg/mL; 标准曲线线性相关系数为0.9903～0.9996,相关性良好;相对标准偏差(RSD)均小于30％, 除低浓度加标水平的甲胺和苯甲胺,其余样品基质加标平均回收率为54.4％～159.7％,大部分胺具有较高的精密度与准确度.将本方法应用于广州城区PM2.5样品的检测, 共检出有机胺9种,其中甲胺、二甲胺和二丁胺约占9种有机胺总和的90％,是PM2.5中主要胺类物质,而丙胺浓度最低,浓度小于1.0 ng/m3.     

Rapid extraction of water soluble organic compounds from airborne particulate matter.

Water soluble organic compounds (WSOC) in airborne particulate matter (PM) have received considerable attention in recent years due to their abundance and their importance in atmospheric processes. The analysis of WSOC is necessary for quantifying the relative contribution of individual organic compounds to the total WSOC mass. In the present work, we evaluated the performance of a microwave-assisted extraction (MAE) method for the determination of WSOC in PM and compared the data with those of a conventional ultrasonic extraction (USE). The experimental results showed that the MAE method requires a shorter extraction time (5 min) compared to USE. The isolated water-soluble organic fraction of PM was subsequently analyzed using ion chromatography (IC) for low molecular weight organic acids. The rapid MAE method was used in conjunction with IC for the analysis of organic acids in PM samples, collected from different sources.     

二级热脱附-气相色谱-质谱联用测定大气可吸入颗粒物中的16种多环芳烃

建立了二级热脱附-气相色谱-质谱联用技术测定大气可吸入颗粒物PM10中16种多环芳烃的分析方法。对二级热脱附和色谱-质谱条件进行了优化。实验结果表明,方法的检出限为0.14～0.42 ng/m3,平均加标回收率为52.7%～97.9%,相对标准偏差(RSD)为8.0%～18.4%。与传统方法相比,该方法的样品前处理时间短、有机溶剂的使用量少,是对人体及环境友善的检测技术。该方法已应用于32份实际大气颗粒物样品的分析。     

Hyphenation of a carbon analyzer to photo-ionization mass spectrometry to unravel the organic composition of particulate matter on a molecular level

The carbonaceous fraction of airborne particulate matter (PM) is of increasing interest due to the adverse health effects they are linked to. Its analytical ascertainment on a molecular level is still challenging. Hence, analysis of carbonaceous fractions is often carried out by determining bulk parameters such as the overall content of organic compounds (OC) and elemental carbon (EC) as well as the total carbon content, TC (sum of OC and EC), however, no information about the individual substances or substance classes, of which the single fractions consist can be obtained. In this work, a carbon analyzer and a photo-ionization time-of-flight mass spectrometer (PI-TOF-MS) were hyphenated to investigate individual compounds especially from the OC fractions. The carbon analyzer enables the stepwise heating of particle samples and provides the bulk parameters. With the PI-TOF-MS, it is possible to detect the organic compounds released during the single-temperature steps due to soft ionization and fast detection of the molecular ions. The hyphenation was designed, built up, characterized by standard substances, and applied to several kinds of samples, such as ambient aerosol, gasoline, and diesel emission as well as wood combustion emission samples. The ambient filter sample showed a strong impact of wood combustion markers. This was revealed by comparison to the product pattern of the similar analysis of pure cellulose and lignin and the wood combustion PM. At higher temperatures (450 °C), a shift to smaller molecules occurred due to the thermal decomposition of larger structures of oligomeric or polymeric nature comparable to lignocelluloses and similar oxygenated humic-like substances. Finally, particulate matter from gasoline and diesel containing 10% biodiesel vehicle exhaust has been analyzed. Gasoline-derived PM exhibited large polycyclic aromatic hydrocarbons, whereas diesel PM showed a much higher total organic content. The detected pattern revealed a strong influence of the biodiesel content on the nature of the particulate organic material.     

Chemical characterization of airborne particulate matter in ambient air of Nagoya, Japan, as studied by the multielement determination with ICP-AES and ICP-MS.

The multielement determination of PM(10) (airborne particulate matter smaller than 10 microm) samples, which was collected by a high volume air sampler at the urban site of Nagoya City, was carried out by inductively coupled plasma atomic emission spectrometry (ICP-AES) and inductively coupled plasma mass spectrometry (ICP-MS). The present analytical method was validated by analyzing urban particulate matter standard reference material of NIST SRM 1648. The analytical data for ca. 30 elements in PM(10) samples collected during a period from 8 September to 9 October, 2003, were obtained in the concentration range from sub-microg g(-1) to several-10 mg g(-1), but the data for 18 elements among ca. 30 elements were available for the characterization of PM(10) samples in ambient air, because of problems caused by the filter blanks. Then, the trends concerning the distributions of diverse elements in PM(10) samples were analyzed based on the enrichment factors and size distribution factors. The lithophile and siderophile elements were distributed more than 50% in coarse particle fraction (>2.1 microm), which was derived mainly from natural sources, such as soils and crustal minerals. On the other hand, chalcophile elements were distributed more than 50% in fine particle fraction (<2.1 microm), which was derived mostly from anthropogenic emission sources. The large enrichment of chalcophile elements in PM(10) samples as well as their mining influence factors (MIFs) suggested their wide use in industrial productions.     

Chemical fractionation of elements in airborne particulate matter: primary results on PM10 and PM2.5 samples in the Lazio region (central Italy)

This paper describes how a two-step chemical fractionation method that allows the determination of 17 elements in airborne particulate matter, has been applied to a monitoring campaign of PM10 and PM2.5 in the Lazio region (Italy). This method involved an extraction in a pH buffered aqueous solution followed by a microwave-assisted acid digestion of the residue. With respect to the determination of the total elemental contents, the evaluation of a soluble fraction provides more reliable information on the presence and of the destiny of heavy metals in the environment. Furthermore, the pH buffered extraction conditions chosen, rendered the results independent of the intrinsic acidity of the collected samples and, although the chemical fractionation has a purely operational function, it facilitates the study of the relationship between the distribution of solubility and the different emission sources. Results are discussed in relation to the different concentration and the different degrees of solubility of the elements observed in two sampling sites; one in an urban and one in a rural environment. Since in-parallel sampling of PM2.5 and PM10 were performed in both sites, the influence of particle size is also discussed. Behaviour of some tracers deriving from both vehicular traffic, with particular attention to re-suspended road dusts, and naturally generated particulate matter, such as marine aerosol and Saharian dust, are discussed.     

Use of capillary electrophoresis with chemiluminescence detection for sensitive determination of homocysteine

A sensitive capillary electrophoresis (CE) method with chemiluminescence (CL) detection was developed for the determination of homocysteine (HCys) in human plasma. In this work, N‐(4‐aminobutyl)‐N‐ethylisoluminol was used as tagging reagent to label the analyte for achieving high assay sensitivity. N‐(4‐Aminobutyl)‐N‐ethylisoluminol‐tagged HCys after CE separation reacted with hydrogen peroxide in the presence of horseradish peroxidase, producing CL emission. Experimental conditions for labeling analyte, CE separation, and CL detection were studied. The CL intensity was proportional to the concentration of HCys in the range of 2.5×10^?8 to 5.0×10^?6 M. Detection limit (S/N=3) was 7.6×10^?9 M. Human plasma samples from healthy donors were analyzed by the presented method. HCys levels were found to be in the range of 9.50–15.3 μM.     

Comparative metabolite profiling of carboxylic acids in rat urine by CE‐ESI MS/MS through positively pre‐charged and 2H‐coded derivatization

A new approach to the selective comparative metabolite profiling of carboxylic acids in rat urine was established using CE‐MS and a method for positively pre‐charged and ²H‐coded derivatization. Novel derivatizing reagents, N‐alkyl‐4‐aminomethyl‐pyridinum iodide (alkyl=butyl, butyl‐d9 or hexyl), containing quaternary amine and stable‐isotope atoms (deuterium), were introduced for the derivatization of carboxylic acids. CE separation in positive polarity showed high reproducibility (0.99–1.32% RSD of migration time) and eliminated problems with capillary coating known in CE‐MS anion analyses. Essentially complete ionization and increased hydrophobicity after the derivatization also enhanced MS detection sensitivity (e.g. formic acid was detected at 0.5 pg). Simultaneous derivatization of one sample using two structurally similar reagents, N‐butyl‐4‐aminomethyl‐pyridinum iodide (BAMP) and N‐hexyl‐4‐aminomethyl‐pyridinum iodide, provided additional information for recognizing a carboxylic acid in an unknown sample. Moreover, characteristic fragmentation acquired by online CE‐MS/MS allowed for identification and categorization of carboxylic acids. Applying this method on rat urine, we found 59 ions matching the characteristic patterns of carboxylic acids. From these 59, 32 ions were positively identified and confirmed with standards. For comparative analysis, 24 standard carboxylic acids were derivatized by chemically identical but isotopically distinct BAMP and N‐butyl‐d9‐4‐aminomethyl‐pyridinium iodide, and their derivatization limits and linearity ranges were determined. Comparative analysis was also performed on two individual urine samples derivatized with BAMP and N‐butyl‐d9‐4‐aminomethyl‐pyridinium iodide. The metabolite profiling variation between these two samples was clearly visualized.     

广州大气细粒子中有机碳、元素碳和水溶性有机碳的分布特征

在广州市中山大学采样点进行了为期1年的大气细粒子(PM2.5)采样,监测分析得到PM2.5及有机碳(OC)、元素碳(EC)和水溶性有机碳(WSOC)等组分的质量浓度,并进行了比较和评价分析。结果表明广州市细粒子碳污染较严重。对OC、EC和WSOC质量浓度的月变化和季节变化特征进行了讨论,并分析了原因。OC、EC浓度相关性好,表明OC、EC来源大部分相同。根据OC/EC比值,估算二次有机碳(SOC)量,结果是SOC占OC的1/3。讨论了SOC和SOC/OC比值的季节分布,结果证明SOC夏季生成比冬季多。     

Chemical characterization of particulate matter (PM) and source apportionment study during winter and summer period for the city of Kozani,Greece

Eordaia basin located in northwest of Greece, comprises an area which is characterized by intense energy related activities, including coal burning at four power plants and the associated mining operations. Air samples of inhalable (PM10) and respirable particles (PM2.5) were collected in cold and warm periods in 2010 at an urban background site of Kozani, the major city and capital of the region which is located close to the power plants. Particulate matter concentration, particle-bound polycyclic aromatic hydrocarbons and anionic species concentrations were determined using gravimetric, GC-MS in SIM mode and Ion Chromatography analysis, respectively. For the cold period, the mean PM10 and PM2.5 mass concentration was found to be 19.62 and 14.68 µg m^?3, respectively. Correspondingly, for the warm period, the mean PM10 and PM2.5 values were 35.29 and 25.75 µg m^?3, respectively. In general, the results indicated that the major sources of air pollution in Kozani are traffic, combustion from agricultural activities and lignite power plants emissions, contributing by different percentages to each particle fraction.      

Determination of elemental and ionic compositions for diesel exhaust particles by particle induced X-ray emission and ion chromatography analysis.

The purpose of this study is to clarify the chemical characterization of PM2.5 and PM10 in diesel exhaust particles (DEP). Sampling of PM2.5 and PM10 in DEP was carried out in November 1999 using an automobile exhaust testing system at the National Traffic Safety and Environment Laboratory, with a diesel truck (engine type: direct injection, displacement: 7,961 cc, carrying weight: 2,020 kg, equivalent inertia weight: 5,600 kg) placed on a chassis dynamometer. Sampling conditions included idling, constant speed of 40 km/h, M-15 test pattern and 60%-revolution/40%-load of maximum power. Samples were collected on a polycarbonate membrane filter (Nuclepore, pore size: 0.8 microm) using a MiniVol Portable Air Sampler (Airmetrics Co., Inc.). The concentrations of several elemental and ionic species in the PM2.5 and PM10 samples were determined by particle induced X-ray emission (PIXE) and ion chromatography analysis. PIXE analysis of the PM2.5 and PM10 samples revealed 15 elements, of which Na, Mg, Si, S, Cl, Ca, Fe and Zn were found to be the major components. Ionic species were Cl-, NO2-, NO3-, SO4(2-), Na+, NH4+, K+ and Ca2+. Concentrations of elements and ionic species under the sampling condition of 60%-revolution/40%-load were highest in comparison with those of the other sampling conditions. The elemental and ionic species data were compared for PM2.5 and PM10; PM2.5 concentrations were 70% or more of PM10 concentrations for the majority of elements, and concentrations of ionic species in PM2.5 and PM10 were almost identical.     

Uncertainties of polynuclear aromatic hydrocarbon and carbonyl measurements in heavy-duty diesel emission

In this note we describe the speciated particle-phase PM2.5 polynuclear aromatic hydrocarbon (PAH) and gas-phase carbonyl emissions as collected from a heavy-duty diesel bus outfitted with an oxidation catalyst for exhaust after-treatment. The vehicle was run on a chassis dynamometer during a transient cycle test reproducing a typical city bus route (Azienda Tramviaria Municipalizzata cycle). The diluted tailpipe emissions were sampled for PAH using a 2.5 microm cut size cyclone glass fiber filter assembly, while carbonyls were absorbed onto dinitrophenyl hydrazine-coated silica cartridges. The former compounds were analysed by CGC-MS, the latter by HPLC-UV. Combining the two sets of speciation data resulting from 15 identical dynamometer tests provided a profile of both unregulated organic emissions. PAH emission rates decreased with the number of benzene fused rings. Fluoranthene and pyrene amounted to 90% of total PAHs quantified; six-ring PAHs accounted only for 0.5%. Similarly, formaldehyde and acetaldehyde accounted for approximately 80% of the total carbonyl emissions. Uncertainties of the method in the determination of individual emission factors were calculated. Statistical data processing revealed that all the measurements were quite unaffected by systematic errors and repeatability percentages did not exceed 50% for the majority of components of both groups.     

Preliminary study on air pollution source identification in Xinzhen,Beijing, using NAA and PIXE

A total of 178 aerosol samples in two size fractions, PM10-2.5 (coarse) and PM2.5 (fine), were collected on nucleopore films using a Gent stacked filter unit sampler at the Graduate School of China Nuclear Industrial Group during May 2007 to November of 2009. Black carbon was determined by a reflectometer. A total of 16 elements, Mg, Al, S, Si, P, Cl, Ca, K, Ti, Mn, Fe, Ni, Cu, Zn, As and Pb, were determined by Particle Induced X-ray Emission. Mg, Al, Ca, K and Mn were also determined by Neutron Activation Analysis. Concentrations of all these elements were used to identify possible pollution sources and directions of the airborne particulate matter by means of softwares PMF and CPF. Some extraordinary events, such as sandstorms, firework and transboundary fire smoke were pinpointed by a combination of time series of multielement, relevant meteorological data and softwares Wind rose, Hysplit, and Google earth.     

Pollution characteristics of ambient PM2.5-bound PAHs and NPAHs in a typical winter time period in Taiyuan

The pollution characteristics of ambient fine particulate matter（PM2.5） containing polycyclic aromatic hydrocarbons（PAHs） and nitrated PAHs（NPAHs） in samples collected during a typical winter time period in Taiyuan of China were investigated.The obtained results revealed that the mean mass concentrations of PM2.5,SPAHs（sum of 16 PAHs） and SNPAHs（sum of 3 NPAHs） on PM2.5were161.4 mg/m3,119.8 ng/m3and 0.446 ng/m3,respectively.Diagnostic ratios of PAHs and NPAHs implied that coal consumption might be the main source of the PM2.5pollution.The measured PM2.5mass concentrations,BaP equivalent toxicity（28.632 ng/m3） and individual carcinogenicity index（3.14 10 5） were much higher than those of the recommended safety standards.     

Development of 7-(N,N-dimethylaminosulfonyl)-5-N-(4-N-aminoethyl)piperazino-2,1,3-benzoxadiazole as a water-soluble fluorogenic reagent for the sensitive liquid chromatographic determination of saturated carboxylic acids

A reversed-phase high-performance liquid chromatographic (HPLC) method for the femtomole determination of nine saturated carboxylic acids, n-butyric (C4), n-hexanoic (C6), n-caprylic (C8), n-decanoic (C10), lauric (C12), n-tetradecanoic (C14), palmitic (C16), stearic (C18) and arachidic (C20), based on the condensation reaction of these acids with a newly synthesized water-soluble benzofurazan fluorescent reagent, 7-(N,N-dimethylaminosulfonyl)-4-N-(4-N-aminoethyl)piperazino-2,1,3-benzoxadiazole (DBD-PZ-NH2), was developed. The derivatization reaction proceeds with 1-[3-(dimethylamino)propyl]-3-ethylcarbodiimide (EDC) in the presence of the catalyst 4-(dimethylamino)pyridine (DMAP). A model derivative of the reagent with n-caprylic acid (C8) was synthesized for fluorescence excitation/emission characterization. Depending on the solvents, including water, methanol, acetonitrile, 1,4-dioxane or N.N-dimethyformamide (DMF), the C8 derivative has a fluorescence emission with a fluorescence quantum yield (phi) ranging from 0.01 to 0.20 in the region from 545 to 580 nm. An exponential increase in phi was observed with increasing acetonitrile content. The calculated detection limits (signal-to-noise ratio = 3:1) of the proposed method for the above nine carboxylic acids were 9.1, 4.0, 2.5, 2.2, 2.0, 1.8, 1.2, 1.0 and 1.3 fmol, respectively. Biological samples including Intralipos 20% and rat plasma were analysed satisfactorily.     

Simultaneous determination of aliphatic and aromatic amines in water and sediment samples by ion-pair extraction and gas chromatography-mass spectrometry

A gas chromatography-mass spectrometry (GC-MS) method has been proposed for the determination of aliphatic and aromatic amines in a variety of environmental samples including wastewater, river water, sea water and sediment samples. The method includes ion-pair extraction with bis-2-ethylhexylphosphate (BEHPA), derivatisation of compounds with isobutyl chloroformate (IBCF) and their GC-MS analysis. Aliphatic and aromatic amines were isolated from aqueous samples using BEHPA as ion-pair reagent and derivatised with IBCF for their chromatographic analysis. Solid-liquid extraction of aliphatic and aromatic amines in sediment samples were performed in Soxhlet apparatus with acidic MeOH and ion-pair extraction with BEHPA were carried out for the isolation of amines followed by derivatisation with IBCF. Aliphatic and aromatic amines were then analysed with GC-MS in both electron impact (EI) and positive and negative ion chemical ionisation (PNICI) mode as their isobutyloxycarbonyl (isoBOC) derivatives. The obtained recoveries ranged from 81.0 to 98.0% and the precision of this method, as indicated by the relative standard deviations (RSDs) was within the range of 0.5 and 4.3%. The detection limits obtained from calculations by using GC-MS results based on S/N = 3 were within the range from 0.07 to 0.50 ng/l.     

Environmental PAH analysis by gas chromatography–atmospheric pressure laser ionization–time-of-flight–mass spectrometry (GC-APLI-MS)

The application of polycyclic aromatic hydrocarbon (PAH) analysis by gas chromatography coupled with atmospheric pressure laser ionization and mass spectrometry (GC-APLI-MS) to environmental samples was investigated in the study. The limit of detection for 40 PAH in a standard mixture was 5–100 fg, demonstrating GC-APLI-MS to be a highly sensitive technique and more sensitive by a factor of 100–3,500 compared to GC-MS. Acenaphthylene and cyclopenta[cd]pyrene were not detectable <2,500 fg per injection. To make use of this very high PAH sensitivity, the technique was applied to samples of environmental interest with limited available sample amounts such as particulate matter (PM), soot and a sample from a bioaccumulation test with Lumbriculus variegatus. First, special sample preparation was necessary and ultrasonic extraction proved to be suitable, if a thorough clean-up was performed and plastic materials avoided. By GC-APLI-MS and GC-MS, 224 and 28 single PAH compounds were detected in PM, about 1,000 and 15 in birch soot, and 9 and 2 in worm tissue, respectively, revealing the enormous potential of the method. The selectivity of GC-APLI-MS was shown for a crude oil where >2,200 PAH were detected without any sample preparation.     

Determination of water-soluble and insoluble compounds in size classified airborne particulate matter

The elemental composition of water soluble and acid soluble size-fractionated airborne particulate matter (APM) was investigated. PM2.5 and PM2.5-10 samples were collected every three days from October 2006 to October 2007 in Buenos Aires, Argentina. The collection was performed on Nucleopore® filters using a GENT sampler. Samples containing fine and coarse particles were subjected to an aqueous leaching to obtain information on the dissolution behaviors of ions, metal and metalloids. Key elements namely, Al, Ba, Ca, Cr, Cu, Fe, Mg, Mn, Pb, Se, Ti and Zn were determined in each fraction by inductively coupled plasma optical emission spectrometry (ICP OES). In the aqueous fractions, Cl⁻, SO₄²⁻, Na⁺ and NH₄⁺ were determined by high performance liquid chromatography (HPLC). A (6:2:5) mixture of nitric, hydrochloric and perchloric acids was used for leaching metals from the residual filters. For validation of the extraction procedure, the ICP OES measurements the Standard Reference Material NIST 1648 (Urban particulate matter) was subjected to the same analytical procedure that the samples loaded with APM. Total analyte concentration varied from 333.2 μg g^− 1 (equivalent to 3.7 ng m^− 3) for Ti to 692 mg g^− 1 (equivalent to 2.47 μg m^− 3) for Ca.     

Amino acid profiling in plant cell cultures: an inter-laboratory comparison of CE-MS and GC-MS

A CE-MS method for metabolic profiling of amino acids was developed and used in an integrated functional genomics project to study the response of Medicago truncatula liquid suspension cell cultures to stress. This project required the analysis of more than 500 root cell culture extracts. The CE-MS method profiled 20 biologically important amino acids. The CE-MS method required no sample derivatization prior to injection and used minimal sample preparation. The method is described in terms of CE and MS operational parameters, reproducibility of migration times and response ratios, sample preparation, sample throughput, and reliability. This method was then compared with a previously published report that used GC-MS metabolic profiling for the same tissues. The data reveal a high level of similarity between the CE-MS and GC-MS amino acid profiling methods, thus supporting these as complementary technologies for metabolomics. We conclude that CE-MS is a valid alternative to GC-MS for targeted profiling of metabolites, such as amino acids, and possesses some significant advantages over GC-MS.