Quantification Of Polycyclic Aromatic Hydrocarbons Research Articles

Passive Sampling and Analysis of Naphthalene in Internal Combustion Engine Exhaust with Retracted SPME Device and GC-MS

Exhaust gases from internal combustion engines are the main source of urban air pollution. Quantification of Polycyclic aromatic hydrocarbons (PAHs) in the exhaust gases is needed for emissions monitoring, enforcement, development, and testing of control technologies. The objective was to develop quantification of gaseous naphthalene in diesel engine exhaust based on diffusion-controlled extraction onto a retracted solid-phase microextraction (SPME) fiber coating and analysis on gas chromatography-mass spectrometry (GC-MS). Extraction of naphthalene with retracted fibers followed Fick’s law of diffusion. Extracted mass of naphthalene was proportional to Cg, t, Dg, T and inversely proportional to Z. Method detection limit (p = 0.95) was 11.5 ppb (0.06 mg·m−3) at t = 9 h, Z = 10 mm and T = 40 °C, respectively. It was found that the % mass extracted of naphthalene by SPME needle assembly depended on the type of fiber. Storage time at different temperatures did not affect analyte losses extracted by polydimethylsiloxane (PDMS) 100 µm fiber. The developed method was tested on exhaust gases from idling pickup truck and tractor, and compared side-by-side with a direct injection of sampled exhaust gas method. Time-weighted average (TWA) concentrations of naphthalene in exhaust gases from idling pickup truck and a tractor ranged from 0.08 to 0.3 mg·m−3 (15.3–53.7 ppb).

Review of the quantification techniques for polycyclic aromatic hydrocarbons (PAHs) in food products

ABSTRACTThere is a growing need for accurate detection of trace-level PAHs in food products due to the numerous detrimental effects caused by their contamination (e.g., toxicity, carcinogenicity, and teratogenicity). This review aims to discuss the up-to-date knowledge on the measurement techniques available for PAHs contained in food or its related products. This article aims to provide a comprehensive outline on the measurement techniques of PAHs in food to help reduce their deleterious impacts on human health based on the accurate quantification. The main part of this review is dedicated to the opportunities and practical options for the treatment of various food samples and for accurate quantification of PAHs contained in those samples. Basic information regarding all available analytical measurement techniques for PAHs in food samples is also evaluated with respect to their performance in terms of quality assurance.

Electrochemical degradation of petroleum hydrocarbons (PAHS) from synthetic aqueous solutions

Water separated from crude oil and wastewater discharge from petroleum oil refineries contains significant quantity of dissolved hydrocarbons. Polycyclic aromatic hydrocarbons (PAHs) are major toxicants in wastewater of refineries. It is difficult to treat wastewater containing PAHs due to their recalcitrant property and low solubility. Conventional techniques for the treatment of wastewater are still a concern of toxicity. Electrochemical oxidation process has been found to be a favorable for treating wastewater. Electrodes with high stability and electrocatalytic activity are important factors for a successful electrochemical oxidation of toxic organics in wastewater. In this study titanium anodes were coated with tin, antimony and iridium oxide mixture from their respective salts by thermal decomposition method. FESEM and XRD used for surface characterization of Ti/SnO2–Sb2O5–IrO2 anode. Quantification of PAHs was done using GC–MS. Results confirm the presence of respective oxides on anode surface. Their electrocatalytic capability was tested for degradation of 16 priority PAHs in aqueous solution. Results reveal the complete degradation of naphthalene, acenaphthylene, acenaphthene and fluorene without using NaCl electrolyte. While in the presence of NaCl naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene and pyrene were completely removed. About 98% of total PAHs removal was found at all initial pH values 3, 6, and 9 in the presence of electrolyte. Current study will be helpful in improving quality of petroleum industry wastewater containing PAHs.

Accelerated solvent extraction method for the quantification of polycyclic aromatic hydrocarbons in cocoa beans by gas chromatography–mass spectrometry

An accelerated solvent extraction (ASE) procedure for use with gas chromatography-mass spectrometry (GC-MS) was optimized for the determination of eight polycyclic aromatic hydrocarbons (PAHs) in cocoa beans. Plackett-Burman and rotatable central composite design (RCCD) indicated that three variables affected the recoveries of PAHs during the extraction and purification steps: agitation time in the second liquid-liquid partition, weight of silica gel in the column, and volume of hexane for PAH elution from the column. After obtaining the optimal conditions, a single laboratory method validation was performed. Linearity was demonstrated for benzo[a]pyrene in the concentration range from 0.5 to 8.0mgkg-1 of sample, corresponding to 1.25-20.0μgkg-1 of cocoa on a fat basis. For the other analytes, linearity was observed from 0.75 to 8.0μgkg-1 of sample (1.88-20.0μgkg-1 of cocoa on a fat basis). Significant matrix effects were found for chrysene and benzo[b]fluoranthene. The precision of the method was verified with relative standard deviations (RSDs) ranging from 2.57 to 14.13% and from 4.36 to 19.77% under repeatability and intermediate precision conditions, respectively. The average recoveries of the eight PAHs ranged from 74.99 to 109.73%. These parameters, limits and measurement uncertainties met the performance criteria established by European Union regulations, except for the theoretical limit of detection for chrysene. The method was applied to the analysis of samples of Brazilian cocoa beans, and only one sample was found to have a PAH content above the maximum limit defined by the European Union legislation. This optimized and validated method is intended to be used as part of the official Brazilian monitoring programs investigating contaminants and residues in food.

Determination of polycyclic aromatic hydrocarbons, dibenzothiophene, and alkylated homologs in the lichen Hypogymnia physodes by gas chromatography using single quadrupole mass spectrometry and time-of-flight mass spectrometry

Development of the Athabasca Oil Sands Region in northeastern Alberta, Canada has contributed polycyclic aromatic hydrocarbons (PAHs) and polycyclic aromatic compounds (PACs), which include alkyl PAHs and dibenzothiophenes, to the regional environment. A new analytical method was developed for quantification of PAHs and PACs in the epiphytic lichen bioindicator species Hypogymnia physodes for use in the development of receptor models for attribution of PAH and PAC concentrations to anthropogenic and natural emission sources. Milled lichens were extracted with cyclohexane, and extracts were cleaned on silica gel using automated solid phase extraction techniques. Quantitative analysis was performed by gas chromatography with selected ion monitoring (GC-SIM-MS) for PAHs, and by GC with time-of-flight mass spectrometry (GC-TOF-MS) for PACs. PACs were quantitated in groups using representative reference compounds as calibration standards. Analytical detection limits were ≤2.5ngg−1 for all individual compounds. Precision as measured by laboratory duplicates was variable; for individual analytes above 5ngg−1 the mean absolute difference between duplicates was typically <20%. Selection of single-analyte markers for source attribution should include consideration of data quality indicators. Use of TOF-MS to spectrally characterize PAC group constituents identified significant challenges for the accurate quantitation of PACs with more than two carbons in their side chain(s). Total PAH concentrations in lichen samples ranged from 12 to 482ngg−1. Total PACs in each sample varied from a fraction of total PAHs to more than four times total PAHs. Results of our analyses of H. physodes are compared with other studies using other species of lichens as PAH receptors and with passive monitoring data using polyurethane foam (PUF) samplers in the Athabasca Oil Sands Region (AOSR). This study presents the first analytical methodology developed for the determination of PACs in an epiphytic lichen bioindicator species.

Coupling ASE, SPE and SPME for the Extraction and Quantification of PAH in Passive Samplers and Biological Materials (Pine Needles)

ABSTRACTThe detection and quantification of trace levels of polycyclic aromatic hydrocarbons (PAH) in the atmosphere require specific and sensitive analytical methodologies. Generally, active sampling is used for the collection of these compounds and this method, though effective, is heavy to use in large scale, long campaigns. Passive sampling using XAD®-2 resin and biomonitoring with conifer needles are good alternatives to active sampling. In this article, an analytical method coupling accelerated solvent extraction, purification by solid phase extraction and pre-concentration by solid phase micro-extraction before injection in GC-MS/MS was developed for the easy extraction of 16 PAH from XAD®-2 resin samplers and conifer needles. A sampling campaign was run for 4 weeks to monitor PAH levels in the Strasbourg area (France), using both passive sampling and biomonitoring. Higher PAH concentrations were detected during the first 2 weeks, as heavy rains drained pollutants from the atmosphere in the last 2 weeks. PAH levels were generally stable, except in the suburban site that registered the highest concentrations the first week and the lowest the second. XAD®-2 resin samplers and conifer needles results were in agreement with the duration of the campaign.

Tenax-TA Spiking Approach of Thermal Desorption Coupled to GC–MSMS for the Quantification of PAHs in Indoor Air and Dust

ABSTRACTA method coupling automated thermal desorption and gas chromatography-tandem mass spectrometry was developed and used for the quantification of 16 PAHs (acenaphthene, anthracene, benzo[a]anthracene, benzo[a]pyrene, benzo[b]fluoranthene, benzo[e]pyrene, benzo[g,h,i]perylene, benzo[k]fluoranthene, chrysene, dibenzo[a,h]anthracene, fluoranthene, fluorene, indeno(1, 2, 3)pyrene, naphthalene, phenanthrene and pyrene) in indoor air and dust. Polycyclic aromatic hydrocarbons (PAHs) in indoor air were sampled using Tenax-TA passive samplers (PAS) exposed during 14 days. Indoor dust, collected on filters using a modified vacuum cleaner head equipped with a sieving device, was first extracted using accelerated solvent extractor. The extract was then concentrated and deposed on a Tenax-TA tube prior to analysis. Using the same thermal desorption method for the analysis of two different matrices gives complementary results with good sensitivity. Limit of detection varied between 0.009 and 0.031 ng and between 0.076 and 0.22 ng/g for PAS and dust, respectively. Likewise, limit of quantification varied between 0.03 and 0.10 ng and between 0.253 and 0.733 ng/g. Results showed that indoor PAH concentrations remains constant, whereas outdoor contamination presents high variability depending on conditions.

Chemometric Discrimination Between Smoked and Non-Smoked Paprika Samples. Quantification of PAHs in Smoked Paprika by Fluorescence-U-PLS/RBL

This study presents a strategy for differentiating paprika obtained by means of different drying systems. The differentiation is performed using spectroscopic fluorescence in combination with multivariate analysis. The two groups of samples (smoked or non-smoked paprika) are classified according to the content of some of their fluorescent compounds presented in each group, among which several polycyclic aromatic hydrocarbons (PAHs) are included. These compounds are characteristic in smoked food. The full information of excitation–emission matrices (EEMs) is processed with the aid of unsupervised parallel factor analysis (PARAFAC), PARAFAC supervised by linear discriminant analysis (LDA) and discriminant unfolded partial least squares (DU-PLS). The last algorithm allows an adequate classification of unknown paprika samples. Besides, the quantification of several PAHs in paprika was performed by means of unfolded partial least squares with residual bilinearization (U-PLS/RBL). On this way, three (fluorene, phenantrene, and anthracene) out of the five (fluorene, phenantrene, anthracene, pyrene and chrysene) selected analytes were quantified.

Polydimethylsiloxane-coated partitioning sample collection device for the precise quantification of polycyclic aromatic hydrocarbons in air.

A novel partitioning collection device comprising a glass cartridge packed with poly(dimethylsiloxane)-coated macroporous silica particles was developed for the precise quantification of polycyclic aromatic hydrocarbons in air. The analyte collection and elution performances achieved using different amounts of poly(dimethylsiloxane) coating were quantitatively evaluated. The sample retention power increased with increasing the coating, and more than 250 L of air could be collected without analyte breakthrough at a sampling temperature of 35°C. During the air collection, the moisture in the air was not retained on the particles due to the hydrophobic surface of the sorbent. A complete and rapid elution of the collected analytes from the device was accomplished by the passage of only 10 mL of acetone with ultrasonication for 1 min. The proposed method was successfully applied for the determination of airborne polycyclic aromatic hydrocarbons in tunnel air.

Historical Profiles of Polycyclic Aromatic Hydrocarbons (PAHs) in Marine Sediment Cores from Northwest Spain.

The northwest coast of Spain is characterized by an irregular coastline rich in marine life and with the highest mussel production in Europe. Taking this into account, the characterization of the pollution levels and the sources involved appear necessary. Not only were parent Polycyclic Aromatic Hydrocarbons (PAHs) analysed but also their alkylated homologues. In total, 35 compounds were analyzed in 5 sediment cores. Sediments were collected using a box core dredge and extracted by (Pressurized Liquid Extraction) whilst the quantification of PAHs was performed using gas chromatography coupled to mass spectrometry (GC-MS). The total concentration detected varied from 49.6 to 2489ngg-1 dry weight (d.w.) of which parent PAHs ranged from 44.5 to 2254ngg-1 d.w. and alkylated PAHs varied from 5.04 to 317ngg-1 d.w. Temporal and spatial evolution were outlined and pollution sources were identified along with a possible correlation between this pollution and local history and industry. Most of the PAHs from the superficial samples have a biomass and coal combustion profile, and some specific, localized events are reflected in the total PAH concentration evolution. Moreover, the study of the deepest layers of the sampled cores provides a baseline to develop background concentration values that will help in future sediment quality assessment.

PAHs in corn grains submitted to drying with firewood

Grain drying using firewood as fuel for air heating, with direct fire, is still widely used in Brazil. The combustion of organic material, such as wood, can generate polycyclic aromatic hydrocarbons (PAHs) which are known to have carcinogenic potential. In the present work corn grain drying was carried out at three drying air temperatures: 60°C, 60/80°C and 80°C. Following the drying process, the presence and quantification of PAH in the corn grains was investigated. After extracting the PAHs of the matrix, the material was subjected to analysis by gas chromatography with mass detector. he results showed the presence of seven compounds: fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benzo(a)anthracene and chrysene.

Simultaneous Determination of 13 Priority Polycyclic Aromatic Hydrocarbons in Tehran's Tap Water and Water for Injection Samples Using Dispersive Liquid-Liquid Micro Extraction Method and Gas Chromatography-Mass Spectrometry.

Polycyclic aromatic hydrocarbons (PAHs) are classified as persistent and carcinogenic organic pollutants. PAHs contamination has been reported in water. Many of relevant regulatory bodies such as EU and EPA have regulated the limit levels for PAHs in drinking water. In this study, 13 priority polycyclic aromatic hydrocarbons (PAHs) were determined in tap water samples of Tehran and water for injection. Dispersive liquid-liquid microextraction procedure combined with gas chromatography-mass spectrometry was used for the extraction and determination of PAHs in the samples. Under the optimized conditions, the range of extraction recoveries and relative standard deviations (RSDs) of PAHs in water using internal standard (anthracene-d10) were in the range of 71-90% and 4-16%, respectively. Limit of detection for different PAHs were between 0.03 and 0.1 ngmL(-1). The concentration of PAHs in all tap water as well as water for injection samples were lower than the limit of quantification of PAHs. This is the first study addressing the occurrence of PAHs in water for injection samples in Iran using dispersive liquid-liquid micro extraction procedure combined with gas chromatography-mass spectrometry.

Simultaneous Sample Preparation Method for Determination of 3-Monochloropropane-1,2-Diol and Polycyclic Aromatic Hydrocarbons in Different Foodstuffs

In the present study, a simultaneous sample preparation method for the determination of 3-monochloropropane-1,2-diol (3-MCPD) and polycyclic aromatic hydrocarbons (PAHs) in different foodstuffs has been evaluated. Sample preparation procedure involved acetonitrile extraction/partitioning and cleanup by dispersive solid phase extraction with the final detection by gas chromatography coupled with mass spectrometry. The experiment demonstrated that freezing out of the sample extracts prior to dispersive solid phase extraction (d-SPE) cleanup step gave better results in removal of undesirable matrix constituents although with slightly lower recovery values. The addition of higher amount of MgSO4 has contributed to increased values of polycyclic aromatic hydrocarbon recovery, in contrast to 3-MCPD for which the recoveries were insignificantly lower when MgSO4 was added. Finally, a simultaneous chromatographic measurement has revealed that quantification of PAHs was not effective due to signal enhancement resulted from the presence of derivatisation products. However, the presented concept can be streamlined and an interesting analytical approach providing good validation parameter values: recoveries within the range 50–110 % for PAHs and 76–107 % for 3-MCPD, precision not exceeding 16.5 % (PAHs) and 7.7 % (3-MCPD) and quantification limits lower than 0.9 μg kg−1 for PAHs and 9.3 μg kg−1 for 3-MCPD.

Profile of Atmospheric PAHs in Rawalpindi, Lahore and Gujranwala Districts of Punjab Province (Pakistan)

ABSTRACTIn this study, polyurethane foam passive air samplers (PUF-PAS) were deployed to evaluate the atmospheric concentration levels and ambient exposure of polycyclic aromatic hydrocarbons (PAHs) in Gujranwala, Lahore and Rawalpindi districts of the Punjab Province (Pakistan). The PAHs were extracted from the PUFs disks using Soxhlet extraction assembly, and were further concentrated using rotary evaporator, purified on a column, packed with alumina/silica, and eluted with a solution of dichloromethane:hexane (1:1 v:v). The PAHs quantification was carried out gas-chromatograph equipped with a mass-spectrometer (GC-MS). Regression scatter plots and molecular diagnostic ratios were used to identify and characterize the emission of PAH species from different sources. Among all detected PAHs, a high concentration of naphthalene (Naph) was observed in Lahore (327 pg m–3) and Rawalpindi (316 pg m–3) cities followed by phenanthrene, banzo(a)pyrene, pyrene, benzo(b)florenthene and benzo(k)flourenthene. Our findings revealed that the low molecular weight (LM)-PAHs in Rawalpindi and Gujranwala cities could have possibly originated from a local petroleum refinery and vehicular emissions respectively, whereas the high molecular weight (HM)-PAHs observed in Wazirabad, could be largely related to both biomass and traffic emissions. Results also showed that ~88 percent of the atmospheric PAHs could be attributed to the wood combustions (R2 = 0.88), out of which more than 50 percent of wood combustion were possibly with the brick kiln sector (R2 = 0.53).

Validation of analytical conditions for determination of polycyclic aromatic hydrocarbons in roasted coffee by gas chromatography–mass spectrometry

Polycyclic aromatic hydrocarbons (PAHs) are of significant interest due to their genotoxicity in humans. PAHs quantification in coffee is complex since some of its compounds interfere in the chromatographic analysis, which hinders the reliable determination of the PAHs. Analytical conditions for the ultrasound extraction, purification and quantification of 16 PAHs in roasted coffee were studied. The better extraction efficiency of benzo[a]pyrene (68%) from ground-roasted coffee was achieved with a solvent ratio of Hex:MC (9:1 v/v) and three extraction periods of 20min, followed by alkaline saponification and purification of the extracts. The detection limits were 0.85–39.32ngmL−1, and the quantification limits from 2.84 to 131.05ngmL−1, obtained for fluoranthene and chrysene, respectively. The extraction was effective for most of the analytes, with recoveries of 39.8% dibenzo[ah]anthracene and 69.0% benzo[b]fluoranthene. For coffee roasted in a spouted bed reactor, the summation of the 16 PAHs ranged from 3.5 to 16.4μgkg−1.

Fluorescence Microscopy Analysis of Particulate Matter from Biomass Burning: Polyaromatic Hydrocarbons as Main Contributors

New efficient approaches to the characterization of fly ash and particulate matter (PM) have to be developed in order to better understand their impacts on environment and health. Polycyclic aromatic hydrocarbons (PAH) contained in PM from biomass burning have been identified as genotoxic and cytotoxic, and some tools already exist to quantify their contribution to PM. Optical fluorescence microscopy is proposed as a rapid and relatively economical method to allow the quantification of PAH in different particles emitted from biomass combustion. In this study samples were collected in the flue gas of biomass-combustion facilities with nominal output ranging from 40 kW to 17.3 MW. The fly ash samples were collected with various flue gas treatment devices (multicyclone, baghouse filter, electrostatic precipitator); PM samples were fractionated from the flue gas with a DEKATI® DGI impactor. A method using fluorescence observations (at 470 nm), white-light observations and image processing has been developed with the aim of quantifying fluorescence per sample. Organic components of PM and fly ash, such as PAH, humic-like substances (HULIS) and water-soluble organic carbon (WSOC) were also quantified. Fluorescence microscopy analysis method assessment was first realized with fly ash that was artificially coated with PAH and HULIS. Total amounts of PAH in the three size fractions of actual PM from biomass burning strongly correlated with the intensities of fluorescence. These encouraging results contribute to the development of a faster and cheaper method of quantifying particle-bound PAH.Copyright 2015 American Association for Aerosol Research

Analysis of Polycyclic Aromatic Hydrocarbon, Toxic Equivalency Factor and Related Carcinogenic Potencies in Roadside Soil within a Developing City of Northern India

Preliminary analysis was performed to assess contamination levels in roadside soils, distribution behavior and human exposure with Polycyclic Aromatic Hydrocarbons (PAHs) during summer, winter, rainy, and autumn during 2013 in one of the developing cities of northern India. The concentration of PAHs was measured at ten different locations (at 1, 2, and 3 m) from roadside soil. Recovery range was 30% and 80% with lower value corresponding to the lower molecular weight PAHs compound. Identification and quantification of PAHs was done by GC-FID. Average PAHs concentration (city average) was found to be 16.53, 4.04, 17.49, and 7.82 μg g−1, during summer, winter, autumn, and the rainy seasons, respectively. Average concentration of low and high carcinogenic PAHs during summer, winter, autumn, and rainy was 5.1 and 31.29, 2.1 and 6.4, 4.74 and 35.08, 3.97 and 12.77μg g−1, respectively. The average ratio of low and high carcinogenic PAHs was found to be 1:6, 1:3, 1:7.6, and 1:3.21 during summer, winter, autumn, and the rainy seasons at most intercepts. Dib(ah)A and B(a)P were the two individual PAHs found in highest concentration during summer, winter, and the rainy seasons, whereas B(a)P and IP were individual PAHs found in highest concentration during autumn. It was also analyzed that high carcinogenic PAHs concentration was quite higher (around 85%) in comparison to low carcinogenic PAHs (around 15%) at most intercepts. This article also deals with the behavior of PAHs at places of average/high population and traffic density intercepts. Five-ringed PAHs were in highest concentration at all intercepts and seasons. Two-tailed T test was applied for authenticity of the data and results. Toxic equivalency factor of B(a)P and Dib(ah)A was maximum as compared to other PAHs.

Determination of Polycyclic Aromatic Hydrocarbons in Camellia Oil by Gel Permeation and High-Performance Liquid Chromatography

A rapid method for the quantification of polycyclic aromatic hydrocarbons in camellia oil is reported. The analytes were extracted from camellia oil using 1:1 (v/v) cyclohexane/ethyl acetate, isolated by gel permeation chromatography, and determined by high-performance liquid chromatography with fluorescence detection. The method features good sensitivity, as the limits of quantification were from 0.33 to 0.67 microgram per kilogram, which are lower than those of regulatory maximum residue limits. Intra- and inter-day precision ranged from 1.19 to 4.52 percent and 1.86 to 3.56 percent, respectively. The recoveries were 79.3–87.9, 85.3–93.4, and 89.6–97.3 percent at fortified levels of 10, 25, and 50 microgram per kilogram, respectively. Moreover, the method is rapid, requiring less than three hours, in comparison to traditional approaches, which require more than twenty-four hours. The developed method was also inexpensive in terms of solvent use and employed to determine polycyclic aromatic hydrocarbons in five camellia oil products. High concentrations of acenaphthene, benz[a]anthracene, benzo[b]fluoranthene, benzo[k]fluoranthene, and benzo[a]pyrene were present in samples produced through extrusion and high temperature pressing. The results suggest that camellia oil processing should be monitored to minimize the presence of polycyclic aromatic hydrocarbons.

PAHs in the Ría de Arousa (NW Spain): A consideration of PAHs sources and abundance

Analysis of 35 parental and alkylated homologues of PAHs (Polycyclic Aromatic Hydrocarbons) was carried out in eleven marine sediment samples collected along a central transect in the biggest Galician ría. The samples were collected using a box-core dredge and, after freeze-drying, were kept frozen until analysis. The sediments were extracted by PLE (Pressurized Liquid Extraction) procedure and the quantification of PAHs was performed using gas chromatography coupled to mass spectrometry (GC–MS) with the aid of deuterated PAH internal standards. The total concentration of studied PAHs (Σ35PAHs) ranged from 44.8 to 7901ngg−1 dry weight (d.w.). The highest PAH concentrations were found in sediments collected near the harbour (7901ngg−1) and the cleanest positions were located in the outer zone of the ría.To date, these results are the first data presented in the area so they could be used for regular monitoring and control of future pollution episodes.

Quantification of PAHs and oxy-PAHs on airborne particulate matter in Chiang Mai, Thailand, using gas chromatography high resolution mass spectrometry

An analytical method using gas chromatography high resolution mass spectrometry was developed for the determination of 16 polycyclic aromatic hydrocarbons (PAHs) and 12 oxygenated PAHs (of which 4 diketones, 3 ketones, 4 aldehydes and one anhydride) on atmospheric particulate matter with an aerodynamic diameter less than 10μm (PM10). The magnetic sector mass spectrometer was run in multiple ion detection mode (MID) with a mass resolution above 10 000 (10% valley definition) and allows for a selective accurate mass detection of the characteristic ions of the target analytes. Instrumental detection limits between 0.04pg and 1.34pg were obtained for the PAHs, whereas for the oxy-PAHs they ranged between 0.08pg and 2.13pg. Pressurized liquid extraction using dichloromethane was evaluated and excellent recoveries ranging between 87% and 98% for the PAHs and between 74% and 110% for 10 oxy-PAHs were obtained, when the optimum extraction temperature of 150°C was applied. The developed method was finally used to determine PAHs and oxy-PAHs concentration levels from particulate matter samples collected in the wet season at 4 different locations in Chiang Mai, Thailand (n=72). This study brings forward the first concentration levels of oxy-PAHs in Thailand. The median of the sum of the PAHs and oxy-PAHs concentrations was 3.4ng/m3 and 1.1ng/m3 respectively, which shows the importance of the group of the oxy-PAHs as PM10 constituents. High molecular weight PAHs contributed the most to the ∑PAHs. For example, benzo[ghi]perylene was responsible for 30–44% of the ∑PAHs. The highest contribution to ∑oxy-PAHs came from 1,8-napthalic anhydride (26–78%), followed by anthracene-9,10-dione (4–27%) and 7H-benzo[de]anthracene-7-one (6–26%). Indications of the degradation of PAHs and/or formation of oxy-PAHs were observed.