Identification, characterization and quantitation of pyrogenic polycylic aromatic hydrocarbons and other organic compounds in tire fire products

On 15 August 2001, a tire fire took place at the Pneu Lavoie Facility in Gatineau, Quebec, in which 4000 to 6000 new and recycled tires were stored along with other potentially hazardous materials. Comprehensive gas chromatography-mass spectrometry (GC-MS) analyses were performed on the tire fire samples to facilitate detailed chemical composition characterization of toxic polycyclic aromatic hydrocarbons (PAHs) and other organic compounds in samples. It is found that significant amounts of PAHs, particularly the high-ring-number PAHs, were generated during the fire. In total, 165 PAH compounds including 13 isomers of molecular weight (MW) 302, 10 isomers of MW 278, 10 isomers of MW 276, 7 isomers of MW 252, 7 isomers of MW 228, and 8 isomers of MW 216 PAHs were positively identified in the tire fire wipe samples for the first time. Numerous S-, O-, and N-containing PAH compounds were also detected. The identification and characterization of the PAH isomers was mainly based on: (1) a positive match of mass spectral data of the PAH isomers with the NIST authentic mass spectra database; (2) a positive match of the GC retention indices (I) of PAHs with authentic standards and with those reported in the literature; (3) agreement of the PAH elution order with the NIST (US National Institute of Standards and Technology) Standard Reference Material 1597 for complex mixture of PAHs from coal tar; (4) a positive match of the distribution patterns of PAH isomers in the SIM mode between the tire fire samples and the NIST Standard Reference Materials and well-characterized reference oils. Quantitation of target PAHs was done on the GC-MS in the selected ion monitoring (SIM) mode using the internal standard method. The relative response factors (RRF) for target PAHs were obtained from analyses of authentic PAH standard compounds. Alkylated PAH homologues were quantitated using straight baseline integration of each level of alkylation.     

Differentiation of isomeric polyaromatic hydrocarbons by electrospray Ag(I) cationization mass spectrometry

Abundant Ag(I)-cationized complexes of 13 polyaromatic hydrocarbons (PAHs), [Ag+PAH](+) and [Ag+2(PAH)](+), were readily generated by electrospray ionization (ESI). In-source collision-induced dissociation (CID) of the [Ag+2(PAH)](+) complex yielded the monomer complex [Ag+PAH](+), which fragmented further to yield the radical molecular ion [PAH](+.). Based on significant differences in relative intensities of [Ag+2(PAH)](+), [Ag+PAH](+) and [PAH](+.), isomeric PAHs can be differentiated. The [PAH](+.)/[Ag+PAH](+) ion intensity ratio was found to increase with decreasing ionization potentials (IPs) of PAHs. The ratio was significantly different for the isomeric PAHs studied over a wide range of PAH concentrations (1.6-100 nmol/mL), and showed good measurement reproducibility; the coefficient of variation of inter-day measurements was in the range 3-12% for four representative PAHs (n = 5). Detection limits for phenanthrene, pyrene, chrysene and benzo[a]pyrene, in the form of the monomer complexes [(107)Ag+PAH](+) and measured in the selected-ion monitoring (SIM) mode, were 0.31, 0.63, 0.16 and 1.25 pmol/5 microl injection, respectively (S/N ratio approximately 2-3).     

全氯代多环芳烃的大气压化学电离质谱

８种全氯代多环芳烃的大气压化学电离质谱（ＡＰＣＩ－ＭＳ）测试结果表明,在ＡＰＣＩ离原中,所有全氯代多环芳烃均能形成质量较样品分子量少１９的负离子,该类负离子是样品分子离子解离一个氯原子后再结合一个氧原子的产物。当样品含有一个五元环时,仍能观察到样品的分子离子峰。ＡＰＣＩ－ＭＳ是一种全氯代多环芳烃或其它弱极性有机物的理想质谱分析方法。     

Rapid analysis of svoc in aerosols by desorption electrospray ionization mass spectrometry

Desorption electrospray ionization mass spectrometry (DESI-MS) was applied for the first time to the analysis of semivolatile organic compounds (SVOC) in atmospheric aerosols. We took polycyclic aromatic hydrocarbons (PAHs) as representatives of SVOCs. The DESI-MS conditions were optimized and the limit of detection for PAHs was about 10 pg with 5 s sampling time. PAHs from both laboratory-made biomass burning aerosols and ambient aerosols were selectively and rapidly analyzed without extraction or preconcentration. The observed PAH species and their relative ion intensities are discussed. This work demonstrates that DESI-MS is a promising method for rapid semiquantitative analysis of SVOC in atmospheric aerosols.     

Trace level analysis of polycyclic aromatic hydrocarbons in surface waters by solid phase extraction (SPE) and gas chromatography-ion trap mass spectrometry (GC-ITMS).

Ontario Provincial Water Quality Objectives for polycyclic aromatic hydrocarbons (PAHs) in surface waters require low parts per trillion (ng L(-1))/high parts per quadrillion (pg L(-1)) detection limits. To meet these monitoring requirements, a solid phase extraction-gas chromatography-ion trap mass spectrometry (SPE-GC-ITMS) method was developed. Seventeen priority PAHs commonly monitored in surface and drinking waters were examined using an external ionization ion trap mass spectrometer operated in selected ion monitoring (SIM) mode. Under 70 eV electron ionization (El) conditions, both the quantitative [M]+* ion and confirmatory [M - 2H]+* ion were formed in classical abundance ratios. Each of these ion species was isolated in the ion trap using a specific scan function. However, to overcome poor levels of confirmatory ion abundance which otherwise restrict PAH method detection limits (MDLs), the abundance of [M - 2H]+* ions was augmented during isolation by causing the dissociation of [M]+* with the broad-band waveform used for high mass ion ejection. Augmenting the [M - 2H]+* signal intensity facilitated the achievement of MDLs of approximately 1 ng L(-1). PAHs in surface water samples that were not detected by current Ontario Ministry of the Environment high-performance liquid chromatography (HPLC)-fluorescence and GC-single-stage quadrupole mass spectrometry methods were detected and quantified using the ion trap mass spectrometry SIM method. The data produced by all three methods on natural water samples fortified at sub-parts per billion (ppb) levels were comparable. When applied to Standards Council of Canada/Canadian Association for Environmental Analytical Laboratories (SCC/CAEAL, www.CAEAL.ca) accreditation audit samples, the SPE-GC-ITMS method results met all performance evaluation criteria.     

Identification and characterization of polycyclic aromatic hydrocarbons in coking wastewater sludge

GC‐MS analysis was performed on the coking sludge from a coking wastewater treatment plant (WWTP) to allow detailed chemical characterization of polycyclic aromatic hydrocarbons (PAHs). The identification and characterization of the isomers of PAHs was based on a positive match of mass spectral data of their isomers with mass spectra databases or based on a comparison of electron impact ionization mass spectra and retention times of target compounds with those reference compounds. In total, 160 PAH compounds including numerous N‐, O‐, S‐, OH‐, and Cl‐containing derivatives were positively identified for the first time. Quantitative analysis of target compounds was performed in the selected ion‐monitoring mode using the internal standard method. The total concentrations of selected compounds in the coking sludge samples from the anaerobic tank, aerobic tank, hydrolytic tank, and secondary clarifier of the WWTP ranged from 1690 ± 585 to 6690 ± 522 mg/kg, which were much higher than those in other industrial and municipal sludges. PAHs with four and five rings were found to be the dominant compounds, and diagnostic ratios of these compounds suggested that they had the characteristics of coal combustion and pyrolysis.     

Analysis of polycyclic aromatic hydrocarbons by liquid chromatography/tandem mass spectrometry using atmospheric pressure chemical ionization or electrospray ionization with tropylium post-column derivatization

Polycyclic aromatic hydrocarbons (PAHs) with four to six rings are potent carcinogens. This study analyzed ten of the sixteen US EPA priority PAHs using reversed-phase liquid chromatography/tandem mass spectrometry (LC/MS/MS) in selected reaction monitoring mode with two ionization sources: positive atmospheric pressure chemical ionization (APCI+) or positive elecrtrospray ionization (ESI+) with tropylium post-column derivatization. Several factors were investigated, including mobile phases, stationary phases of columns and chromatographic temperature, to determine how optimal separation and sensitivity might be achieved. Methanol used as an organic mobile phase provided better sensitivities for most PAHs than acetonitrile, although some PAHs co-eluted. Acidic buffers did not increase analyte signals. Use of Restek Pinnacle II PAH columns (250 x 4.6 mm or 250 x 2.1 mm, 5 microm) with water/acetonitrile gradient at 27 degrees C made possible a good separation of the ten analytes. [M]+. were the best precursor ions in both APCI and ESI, although fluoranthene could not be detected in ESI mode when tropylium post-column derivatization was performed. [M-28]+ and [M-52]+ were the major product ions of PAHs after collision-induced dissociation, a result of neutral losses of C(2)H(4) and (C(2)H(2))(2), respectively. Chromatographic separation for PAH isomers was crucial because the mass spectra were so similar that even MS/MS could not distinguish them from each other. The recoveries of sample preparations of PAHs spiked onto air-sampling filters ranged between 77.5 and 106% with relative standard deviations between 1.1 and 15.9%. This method was validated by analyzing NIST SRM 1649a (urban dust), producing results comparable with the certified PAH concentrations. The detection limits using APCI and ESI interfaces, defined as three times the noise levels, ranged between 0.23 and 0.83 ng and between 0.16 and 0.84 ng of on-column injection, respectively.     

Fragmentation study of protonated chalcones by atmospheric pressure chemical ionization and tandem mass spectrometry

Fragmentation mechanisms of protonated chalcone and its derivatives with different functional groups were investigated by atmospheric pressure chemical ionization with tandem mass spectrometry (MS/MS). The major fragmentation pathways were loss of the phenyl group from the A or B ring, combined with loss of CO. Losses of H(2)O and CO from the precursor ions of [M+H](+) are proposed to occur via rearrangements. Elimination of water from protonated chalcones was observed in all the title compounds to yield a stable ion but it was difficult to obtain skeletal fragmentation of a precursor ion. Loss of CO was found in the MS/MS spectra of all the compounds except the nitro-substituted chalcones. When the [M+H--CO](+) ion was fragmented in the MS/MS experiments, there were distinctive losses of 15 and 28 Da, as the methyl radical and ethylene, respectively. The ion at m/z 130, found only in the nitro-substituted chalcones, was assigned as C(9)H(6)O by Fourier transform ion cyclotron resonance (FTICR)-MS/MS; m/z 130 is a common fragment ion in the electron ionization (EI) spectra of chalcones. In order to more easily distinguish the constitutional isomers of these chalcones, breakdown curves were produced and these provided strong support in this study.     

Quantitative analysis of polycyclic aromatic hydrocarbons using high-performance liquid chromatography-photodiode array-high-resolution mass spectrometric detection platform coupled to electrospray and atmospheric pressure photoionization sources

Polycyclic aromatic hydrocarbons (PAHs) are common pollutants present in atmospheric aerosols and other environmental mixtures. They are of particular air quality and human health concerns as many of them are carcinogenic toxins. They also affect absorption of solar radiation by aerosols, therefore contributing to the radiative forcing of climate. For environmental chemistry studies, it is advantageous to quantify PAH components using the same analytical technics that are commonly applied to characterize a broad range of polar analytes present in the same environmental mixtures. Liquid chromatography coupled with photodiode array and high-resolution mass spectrometric detection (LC-PDA-HRMS) is a method of choice for comprehensive characterization of chemical composition and quantification of light absorption properties of individual organic compounds present in the environmental samples. However, quantification of non-polar PAHs by this method is poorly established because of their imperfect ionization in electrospray ionization (ESI) technique. This tutorial article provides a comprehensive evaluation of the quantitative analysis of 16 priority pollutant PAHs in a standard reference material using the LC–MS platform coupled with the ESI source. Results are further corroborated by the quantitation experiments using an atmospheric pressure photoionization (APPI) method, which is more sensitive for the PAH detection. The basic concepts and step-by-step practical guidance for the PAHs quantitative characterization are offered based on the systematic experiments, which include (1) Evaluation effects of different acidification levels by formic acid on the (+)ESI-MS detection of PAHs. (2) Comparison of detection limits in ESI+ versus APPI+ experiments. (3) Investigation of the PAH fragmentation patterns in MS² experiments at different collision energies. (4) Calculation of wavelength dependent mass absorption coefficient (MAC_λ) of the standard mixture and its individual PAHs using LC-PDA data. (5) Assessment of the minimal injected mass required for accurate quantification of MAC_λ of the standard mixture and of a multi-component environmental sample.     

Analysis of high-molecular-mass polycyclic aromatic hydrocarbons in environmental samples using liquid chromatography-atmospheric pressure chemical ionization mass spectrometry

Polycyclic aromatic hydrocarbons (PAHs) with molecular masses higher than 300 u were analysed using LC-atmospheric pressure chemical ionization (APCI) MS in extracts of environmental samples from Hamilton, Canada including zebra mussels from Hamilton Harbour, air particulate and coal tar. The LC-APCI-MS profiles of three molecular mass classes of PAHs (326 u, 350 u and 374 u) were compared to identify potential sources of PAH contamination in Hamilton Harbour. The Hamilton air particulate profile was also compared with an urban air reference standard (NIST SRM 1649) from Washington, DC, USA. Profiles of all extracts were similar and suggested an environmental predominance of PAHs within the three isomeric molecular mass classes studied. However, PAHs of molecular mass 326 u and 350 u were detected in extracts of coal tar and zebra mussels from Hamilton Harbour but were not detected in Hamilton air. These results indicated that some high-molecular-mass PAHs may be characteristic of contamination by coal tar.     

Negative ions generated by reactions with oxygen in the chemical ionization source. II. The use of wall-catalyzed oxidation reactions for differentiation of polycyclic aromatic hydrocarbons and their methyl derivatives

Polycyclic aromatic hydrocarbons (PAH) undergo wall-catalyzed oxidation reactions, in conjunction with electron-and ion-molecule reactions, when oxygen is present in the chemical ionization source. Under conditions that promote these wall-catalyzed oxidation reactions (addition of oxygen, elevated ion source temperature) oxidized products are easily detected by measurement of the negative ion chemical ionization (NICI) mass spectra. The NICI mass spectra are dominated by ions that result from electron-capture ionization of oxidation products such as ketones, quinones and anhydrides. In this study the NICI mass spectra of 30 PAH and 46 methyl-substituted PAH were measured. These spectra can be used to differentiate certain isomeric PAH based upon differences in molecular structure. Of particular interest are ions that appear in the spectra of methyl-substituted PAH, which can provide information regarding the position of methyl substituents.     

紫外检测器-荧光检测器串联的HPLC法测定火力发电厂环境中的多环芳烃

 建立了一种紫外检测器(UVD)与荧光检测器(FLD)串联的HPLC法,检测了火力发电厂环境中的多环芳烃（PAH）化合物。在所选择的色谱条件下12个PAH可得到完全分离,其中萘等8个PAH用UVD检测,苯并〔a〕芘等4个PAH用FLD检测。应用该方法对湖南省内几家火力发电厂的废水、烟道气、粉煤灰中的12个PAH进行了实测,效果良好。     

Comparison of immunoassay and gas chromatography-mass spectrometry for measurement of polycyclic aromatic hydrocarbons in contaminated soil

Polycyclic aromatic hydrocarbons (PAHs) are frequently encountered in the environment and may pose health concerns due to their carcinogenicity. A commercial enzyme-linked immunosorbent assay (ELISA), was evaluated as a screening method for monitoring PAHs at contaminated sites. The ELISA was a carcinogenic PAH (C-PAH) RaPID assay testing kit that cross-reacts with several PAHs and utilizes benzo[a]pyrene (BaP) as a calibrator. Soil samples were extracted with 50% acetone in dichloromethane (DCM) for analysis by ELISA and gas chromatography-mass spectrometry (GC-MS). The overall method precision was within ±30% for ELISA and within ±20% for GC-MS. Recovery data for spiked soils ranged from 46 to 140% for BaP as determined by ELISA. Recoveries data of the GC-MS surrogate standards, 2-fluorobiphenyl and chrysene, were greater than 70%. The GC-MS procedure detected a total of 19 priority PAHs (2-6-ring PAHs) including seven probable human carcinogens (4-6-ring B2-PAHs). The ELISA results were compared to GC-MS summation results for the total 19 target PAHs as well as for the subset of the seven B2-PAH compounds. For all soil samples, the PAH concentrations derived from ELISA were greater than the sum of B2-PAH concentrations obtained by GC-MS. ELISA determinations were also frequently greater than the results obtained by GC-MS for the total 19 PAH compounds. This discrepancy can be expected, since the ELISA is a screening assay for the detection of several related PAHs while the GC-MS procedure detects priority PAH compounds. Thus, only a subset of PAHs (e.g. 19 PAHs) in the soil samples were measured by GC-MS while additional PAHs, including alkylated PAHs, and PAH derivatives have been demonstrated to be cross-reactive in the C-PAH ELISA. Results of paired tests show that the PAH data from ELISA and GC-MS methods are significantly different (P<0.001), but highly correlated. The ELISA data had a strong positive relationship with the GC-MS summation data for the B2-PAHs as well as for the 19 PAHs targeted by the GC-MS method. Results indicate that the ELISA may be useful as a broad screen for monitoring PAHs in environmental samples.     

Comparison of flow injection analysis electrospray mass spectrometry and tandem mass spectrometry and electrospray high-field asymmetric waveform ion mobility mass spectrometry and tandem mass spectrometry for the determination of underivatized amino acids

Twenty proteinogenic amino acids (AAs) were determined without derivatization using flow injection analysis followed by electrospray ionization mass spectrometry and tandem mass spectrometry (ESI-MS and ESI-MS/MS) and electrospray ionization high-field asymmetric waveform ion mobility mass spectrometry and tandem mass spectrometry (ESI-FAIMS-MS and ESI-FAIMS-MS/MS), in positive and negative ionization modes. Three separate sets of ESI-FAIMS conditions were used for the separation and detection of the 20 AAs. Typically ESI-FAIMS-MS showed somewhat improved sensitivity and significantly better signal-to-noise ratios than ESI-MS mainly due to the elimination of background noise. However, the difference between ESI-FAIMS-MS and ESI-MS/MS was significantly less. ESI-FAIMS was able to partially or completely resolve all the isobaric amino acid overlaps such as leucine, isoleucine and hydroxyproline or lysine and glutamine. Detection limits for the amino acids in ESI-FAIMS-MS mode ranged from 2 ng/mL for proline to 200 ng/mL for aspartic acid. Overall, ESI-FAIMS-MS is the preferred method for the quantitative analysis of AAs in a hydrolyzed yeast matrix.     

Negative ion laser desorption ionization time-of-flight mass spectrometry of nitrated polycyclic aromatic hydrocarbons

Nitrated polycyclic aromatic hydrocarbons (nitro-PAHs) are widespread environmental pollutants that are generated by incomplete combustion and by atmospheric transformation of polycyclic aromatic hydrocarbons (PAHs). Many nitro-PAH compounds are potent genotoxins and some are direct acting mutagens. Detection of nitro-PAHs in aerosols is complicated by small sample sizes and nitro-PAH abundances that are 1–2 orders of magnitude less than analogous unsubstituted PAHs. Selective detection of several nitro-PAHs by using laser desorption ionization time-of-flight mass spectrometry in negative ion mode has been achieved. Desorption and ionization of nitro-PAHs were effected by using pulsed UV radiation at 266 and 213 ran. Intense molecular anions were observed in addition to fragments identified as CN^? and NO ₂ ^? , which were characteristic indicators of the presence of nitro-PAHs. Selective detection of nitro-PAHs in negative ion mode was demonstrated in the analysis of a diesel particulate sample.     

Ultraviolet laser desorption/ionization mass spectrometry of single‐core and multi‐core polyaromatic hydrocarbons under variable conditions of collisional cooling: insights into the generation of molecular ions,fragments and oligomers

The ultraviolet laser desorption/ionization of polyaromatic hydrocarbons (PAHs) has been investigated under different background pressures of an inert gas (up to 1.2 mbar of N₂) in the ion source of a hybrid, orthogonal‐extracting time‐of‐flight mass spectrometer (oTOF‐MS). The study includes an ensemble of six model PAHs with isolated single polyaromatic cores and four ones with multiple cross‐linked aromatic and polyaromatic cores. In combination with a weak ion extraction field, the variation of the buffer gas pressure allowed to control the degree of collisional cooling of the desorbed PAHs and, thus, to modulate their decomposition into fragments. The dominant fragmentation channels observed are related to dehydrogenation of the PAHs, in most cases through the cleavage of even numbers of C―H bonds. Breakage of C―C bonds leading to the fragmentation of rings, side chains and core linkages is also observed, in particular, at low buffer gas pressures. The precise patterns of the combined fragmentation processes vary significantly between the PAHs. The highest abundances of molecular PAH ions and cleanest mass spectra were consistently obtained at the highest buffer gas pressure of 1.2 mbar. The effective quenching of the fragmentation pathways at this elevated pressure improves the sensitivity and data interpretation for analytical applications, although the fragmentation of side chains and of bonds between (poly)aromatic cores is not completely suppressed in all cases. Moreover, these results suggest that the detected fragments are generated through thermal equilibrium processes rather than as a result of rapid photolysis. This assumption is further corroborated by a laser desorption/ionization post‐source decay analysis using an axial time‐of‐flight MS. In line with these findings, covalent oligomers of the PAHs, which are presumably formed by association of two or more dehydrogenated fragments, are detected with higher abundances at the lower buffer gas pressures. Copyright © 2014 John Wiley & Sons, Ltd.     

Optimization and validation of HPLC-UV-DAD and HPLC-APCI-MS methodologies for the determination of selected PAHs in water samples

Polycyclic aromatic hydrocarbons (PAHs) are environmental contaminants resulting from emissions of a variety of sources including industrial combustion, discharge of fossil fuels, and residential heating. Because of their mutagenic and carcinogenic properties, the study of PAHs in environmental matrices is of great importance. In this work, the extraction of 9 out of the 16 PAH priority pollutants according to the U.S. Environmental Protection Agency is carried out through liquid-liquid extraction (LLE) and solid-phase extraction (SPE). The determination of PAHs is made by high-performance liquid chromatography with diode-array detection and liquid chromatography-atmospheric pressure chemical ionization mass spectrometry. Between the extraction techniques used, LLE is revealed to be efficient in the extraction of the higher molecular weight PAHs, though SPE is adequate for the extraction of all PAHs. In the real water samples analyzed, no PAH is detected under the analysis conditions used.     

Selective detection of nitrated polycyclic aromatic hydrocarbons by electrospray ionization mass spectrometry and constant neutral loss scanning

The development of a method for selective detection of nitrated polycyclic aromatic hydrocarbons (nitro-PAHs) among other polycyclic aromatic compounds (PACs) is described. The method is based on electrospray ionization mass spectrometry (ESI-MS), performed with a triple quadrupole analyzer and constant neutral loss (CNL) scanning. When subjected to ESI conditions, nitro-PAHs give rise to M(-), [M - H](-) and [M - H + 16](-) ions, which in turn produce fragments by losing 30 u, most probably NO. Other PACs do not undergo such fragmentations, and these differences can be exploited for selective detection of nitro-PAHs among other PACs. Nitro-PAHs can therefore be monitored through the loss of 30 u occurring under negative ion mode ESI conditions. Toward the full development of a screening method for nitro-PAHs, this article first discusses some general aspects of the negative ion mode full-scan ESI mass spectra obtained for these compounds and other PAH derivatives. Because the extent of observation of the loss of 30 u is sensitive to the ESI conditions used, the effects of ionization parameters such as solvent used, declustering voltage, and solvent flow rate are evaluated and discussed. Setting these parameters is very important, especially when interfacing a high performance liquid chromatography (HPLC) system with the ESI source of a triple quadrupole mass spectrometer. Preliminary results of on-line microbore HPLC/ESI-MS separations of PAC standards are presented, and elution/ionization conditions discussed.     

高效液相色谱-电喷雾银离子诱导电离飞行时间质谱定性分析高沸点多环芳烃

建立了高效液相色谱-电喷雾飞行时间质谱联用技术快速鉴别高沸点多环芳烃的方法。多环芳烃经色谱柱分离后,通过柱后添加AgNO3溶液诱导其在电喷雾离子源中电离,生成多环芳烃[M]+及其复合[M+Ag]+和[2M+Ag]+特征离子,根据所获得的各特征离子的精确分子量和分子式,可实现多环芳烃类化合物的快速鉴别。将本方法用于美国环保局(USEPA)规定的16种优先控制多环芳烃及原油中多环芳烃类化合物的分析鉴别,结果表明,四环以上的PAHs质谱信号良好,说明本方法适用于四环以上的高分子量、高沸点多环芳烃类化合物的分析鉴别。