Determination of polycyclic aromatic hydrocarbons by gas chromatography — ion trap tandem mass spectrometry and source identifications by methods of diagnostic ratio in the ambient air of Campo Grande, Brazil

Characterization of Polycyclic Aromatic Hydrocarbons (PAHs) associated with fine aerosols in ambient atmosphere of high-altitude urban environment in Sikkim Himalaya

Polycyclic Aromatic Hydrocarbons (PAHs) compounds are ubiquitous in ambient air due to their persistence, carcinogenicity, and mutagenicity. Gangtok being one of the cleanest cities in India located in Eastern Himalayan region, witnesses high developmental activities with enhanced urbanization affecting the ambient air quality. The present study aims to measure PM_2.5 and PAHs in the ambient atmosphere of the Sikkim Himalaya to understand the influence of natural and anthropogenic activities on aerosol loading and their chemical characteristics. The PM_2.5 samples were collected and analysed for the duration from Jan 2020 to Feb 2021.The seasonal mean concentrations of PM_2.5 and PAHs were observed to be high during autumn and low during summer season. Overall, the annual mean concentration of PM_2.5 was found higher than the prescribed limit of World Health Organization and National Ambient Air Quality Standards. The concentration of the 16 individual PAHs were found to be highest during autumn season (55.26 ± 37.15 ng/m³). Among the different PAHs, the annual mean concentration of fluorene (3.29 ± 4.07 ng/m³) and naphthalene (1.15 ± 3.76 ng/m³) were found to be the highest and lowest, respectively. The Molecular Diagnostic Ratio (MDR) test reveals higher contribution from heavy traffic activities throughout the winter and autumn seasons. The other possible sources identified over the region are fossil fuel combustion, and biomass burning. The multivariate statistical analysis (Multifactor Principal Component Analysis) also indicates a strong association between PM_2.5 /PAHs and meteorological variables across the region in different seasons. The precipitation and wind pattern during the study period suggests that major contribution of the PM_2.5 and PAHs were from local sources, with minimal contribution from long-range transport. The findings are important for comprehending the trends of PAH accumulation over a high-altitude urban area, and for developing sustainable air quality control methods in the Himalayan region.

In-vial solid-phase extraction of polycyclic aromatic hydrocarbons in drug formulations stored in packaging containing rubber

Polycyclic aromatic hydrocarbons (PAHs) are a class of ubiquitous and persistent organic compounds that are significantly teratogenic, carcinogenic and mutagenic. Rubber stoppers commonly used in sterile formulation packaging materials often contain carbon black as the additive to enhance mechanical strength. However, PAHs may be formed during the production of carbon black, which could cause the drug formulations to be contaminated when contacting with the rubber stopper, and then enter the patient's body. The determination of PAHs in drug formulations is challenging, due to their trace amounts and matrix interference. Therefore, sample pretreatment is necessary and important. In this work, a novel technique, named in-vial solid-phase extraction (IVSPE), was developed for the selective extraction and enrichment of 16 PAHs in pharmaceuticals. The coated sample vial was directly used as the container for the whole process of sample pretreatment. As the solid-phase adsorbent, the coating was prepared by successively modifying the inner surface of a sample vial with polydopamine film and octadecylamine. PAHs could be selectively extracted through π-π stacking interaction and hydrophobic interaction, and then desorbed and enriched by a small amount of organic solvent. After systematic optimization of the coating preparation and the extraction process, the limits of detection and quantification of 16 PAHs were in the range of 0.002-0.60 ng mL^-1 and 0.007-2.00 ng mL^-1, respectively. Good linearities and precision of six repeated injections were obtained. The recoveries at three spiked concentration levels in normal saline were in the range of 62.72-106.90% with the relative standard deviation between 0.83% and 6.78%. Finally, PAHs in normal saline and powders for injection were extracted by established IVSPE, followed by separation and detection with high-performance liquid chromatography with a fluorescence detector and diode array detector (HPLC-FLD/DAD). It is worth noting that the preparation conditions of the adsorbent in the IVSPE method are mild, simple and green. Moreover, IVSPE has the advantages of having few work steps and avoiding the risk of contamination, because no special instrumentation or sample transfer is required. IVSPE could also be used for the pretreatment of multiple samples at the same time, which is beneficial to practical applications.

Influence of lockdown caused by the COVID-19 pandemic on air pollution and carcinogenic content of particulate matter observed in Croatia

Due to the pandemic of SARS-CoV-2 in Croatia, all unnecessary activities were prohibited during the designated lockdown period (March-May 2020). With reduced human activity, levels of some air pollutants decreased. In this study, mass concentrations of the PM₁ particle fraction (particulate matter with an equivalent aerodynamic diameter < 1 μm) and polycyclic aromatic hydrocarbons (PAHs) in PM₁ and NO₂ were measured and compared with concentrations measured in the same period the year before. Air pollutant concentrations were measured at two measuring sites: urban residential and urban traffic. Our results show a concentration decrease by 35% for NO₂ and PM₁ particles and by 26% for total PAHs at the traffic measuring site. At the residential measuring site, only concentrations of NO₂ decreased slightly, but PM₁ particles and PAHs were similar to the year before.

Influence of lockdown caused by the COVID-19 pandemic on air pollution and carcinogenic content of particulate matter observed in Croatia

Due to the pandemic of SARS-CoV-2 in Croatia, all unnecessary activities were prohibited during the designated lockdown period (March-May 2020). With reduced human activity, levels of some air pollutants decreased. In this study, mass concentrations of the PM₁ particle fraction (particulate matter with an equivalent aerodynamic diameter < 1 μm) and polycyclic aromatic hydrocarbons (PAHs) in PM₁ and NO₂ were measured and compared with concentrations measured in the same period the year before. Air pollutant concentrations were measured at two measuring sites: urban residential and urban traffic. Our results show a concentration decrease by 35% for NO₂ and PM₁ particles and by 26% for total PAHs at the traffic measuring site. At the residential measuring site, only concentrations of NO₂ decreased slightly, but PM₁ particles and PAHs were similar to the year before.

Pollution Sources and Carcinogenic Risk of PAHs in PM1 Particle Fraction in an Urban Area

Airborne particles are composed of inorganic species and organic compounds. PM₁ particles, with an aerodynamic diameter smaller than 1 μm, are considered to be important in the context of adverse health effects. Many compounds bound to particulate matter, such as polycyclic aromatic hydrocarbons (PAH), are suspected to be genotoxic, mutagenic, and carcinogenic. In this study, PAHs in the PM₁ particle fraction were measured for one year (1/1/2018–31/12/2018). The measuring station was located in the northern residential part of Zagreb, the Croatian capital, close to a street with modest traffic. Significant differences were found between PAH concentrations during cold (January–March, October–December) and warm (April–September) periods of the year. In general, the mass concentrations of PAHs characteristic for car exhausts (benzo(ghi)perylene (BghiP), indeno(1,2,3-cd)pyrene (IP), and benzo(b)fluoranthene (BbF)) were higher during the whole year than concentrations of fluoranthene (Flu) and pyrene (Pyr), which originated mostly from domestic heating and biomass burning. Combustion of diesel and gasoline from vehicles was found to be one of the main PAH sources. The incremental lifetime cancer risk (ILCR) was estimated for three age groups of populations and the results were much lower than the acceptable risk level (1 × 10⁻⁶). However, more than ten times higher PAH concentrations in the cold part of the year, as well as associated health risk, emphasize the need for monitoring of PAHs in PM₁. These data represent a valuable tool in future plans and actions to control PAH sources and to improve the quality of life of urban populations.

Characteristics of polycyclic aromatic hydrocarbons components in fine particle during heavy polluting phase of each season in urban Beijing

Beijing experienced a period of severe atmospheric particulate pollution from 2015 to 2016. In order to acquire the characteristics of polycyclic aromatic hydrocarbons (PAHs) under heavy polluting status, one year sampling campaign was carried out. We selected PM2.5 samples which had the highest concentrations or suffered serious haze-fog weathers in each month. Through the analysis of data from heavily polluting phase, the mean concentrations of PM2.5 and PAHs in winter (369.63 μg m^-3 and 223.60 ng m^-3) were obviously higher than that in other seasons. The concentration of Σ₁₆PAHs ranged from 3.22 to 297.01 ng m^-3, with a mean value of 77.48 ng m^-3. In winter, 4-ring PAH congeners (52.33%) contributed the most in PM2.5, followed by 5-rings (27.05%), 6-rings (11.55%) and 2∼3-rings (9.06%). Summertime measurements showed the highest decline in PAHs concentrations for 3∼5-ring congeners. The diagnostic ratios and PCA analysis manifest that vehicle and combustion emission were major sources and totally occupied 88.57% under heavy polluting stage. Moreover, exponential relationship between LWM/HWM (light/high weight molecule-PAHs) and combustion-derived PAHs, as well as linear relationship between BghiP and ∑PAHs verified that the pollution sources mentioned above affected local atmosphere environment as major sources. The highest total BaP equivalent concentration suggested that toxicity potency under heavy polluting phase was mainly attributed to 5-ring PAHs. Through analysis of carcinogenic-PAHs, potency risk to adults was significantly higher than that to children. BaP, BbF and DahA, which belong to 5-ring congeners, contributed the highest potency carcinogenic risk. BbF in winter, BaP in spring and winter may cause potential risk to local residents.

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

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

Characterization of particulate polycyclic aromatic hydrocarbons in an urban atmosphere of central-southern Spain

Over 1-year period, 13 polycyclic aromatic hydrocarbons (PAHs) associated with particulate matter PM10 have been monitored for the first time in the atmosphere of Ciudad Real, situated at the central-southern Spain. PM10-bound PAHs were collected using a high-volume sampler from autumn 2012 to summer 2013 and were analyzed by HPLC with fluorescence detector. The most abundant PAHs were pyrene, chrysene, benzo[b]fluoranthene, dibenzo[a,h]anthracene and benzo[g,h,i]perylene. The ∑PAH concentrations in Ciudad Real were 888, 368, 259 and 382 pg m(-3) for winter, spring, summer and autumn seasons, respectively. The diurnal variation of PAH was also investigated presenting the highest concentrations during the evening (19:00-23:00). Benzo[a]pyrene concentrations ranged from 2.4 to 110 pg m(-3), these values are lower than the target value proposed by the European legislation, 1 ng m(-3). Diagnostic ratios were used to identify potential sources of PAHs. Results suggest that vehicle emissions are the major source of identified PAHs, with a higher contribution of diesel engines although other anthropogenic sources could also have an impact on the PAH levels.

Carcinogenic activity of polycyclic aromatic hydrocarbons bounded on particle fraction

Polycyclic aromatic hydrocarbons (PAHs) originate from a variety of natural and industrial processes. In this paper, concentrations of nine PAHs in PM10 particle fraction were measured concurrently at four different sites (rural, urban residential, urban traffic, and residential-industrial) in continental Croatia. Measurements at all of the four sites showed much higher average concentrations for all of the PAHs in the winter period. The highest winter average values were measured at the industrial site and the lowest at the rural and the urban residential site. In the summer, the highest average values were also measured in the industrial area, except for benzo(ghi)perylene and indeno(1,2,3-cd)pyrene, which showed the highest average values in the rural area. Factor analysis has been applied to PAH concentrations to identify their potential sources. Extracted factors have been interpreted on basis of previous studies and weather conditions. The diagnostic ratios calculated in this study indicated mixed sources at all of the sites. The contribution of gasoline and diesel from traffic was significant at all of the sites except for the urban industrial. In the winter, potential PAH sources also arose from wood combustion. The industrial site differed from the other sites with the highest influence of diesel sources and refinery during the summer months. The contribution of BaP in total carcinogenic activity exceeded 50 % in both seasons at all of the measured sites, which suggests that BaP could be suitable as a marker of the carcinogenic potential of a PAH mixture.

Risk assessment of the presence of polycyclic aromatic hydrocarbons (PAHs) in coastal areas of Thailand affected by the 2004 tsunami

The total concentrations of twelve, likely carcinogenic, polycyclic aromatic hydrocarbons (PAHs) (i.e., phenanthrene (Phe), anthracene (An), fluoranthene (Fluo), pyrene (Pyr), benz[a]anthracene (B[a]A), chrysene (Chry), benzo[b]fluoranthene (B[b]F), benzo[k]fluoranthene (B[k]F), benzo[a]pyrene (B[a]P), indeno[1,2,3-cd]pyrene (Ind), dibenz[a,h]anthracene (D[a,h]A), and benzo[g,h,i]perylene (B[g,h]P) in backwash deposits of the 2004 Khao Lak tsunami were carefully investigated and compared with the concentrations of world marine sediments (WMS). In general, ∑12PAHs in this study (i.e., 69.43 ± 70.67 ng g(-1)) were considerably lower than those values observed in marine sediments from Boston (54,253 ng g(-1)), coastal sediments from Barcelona Harbour (15,069 ng g(-1)), and riverine sediment from Guangzhou Channel (12,525 ng g(-1)), but were greater than values from coastal sediments in Rosas Bay (12 ng g(-1)), Santa Ponsa Bay (26 ng g(-1)) and Le Planier (34 ng g(-1)). The total toxic benzo[a]pyrene equivalent (TEQ(Carc)) values calculated for Khao Lak coastal sediments (KCS), Khao Lak terrestrial soils (KTS), and Songkhla Lake sediments (SLS) were 10.3 ± 12.2 ng g(-1), 16.0 ± 47.7 ng g(-1), and 5.67 ± 5.39 ng g(-1), respectively. Concentrations of PAHs at all study sites resulted in risk levels that fell into the "acceptable" range of the US EPA model and were much lower than those of other WMS. The cancer risk levels of PAH content in KCS ranged from 7.44 × 10(-8) to 2.90 × 10(-7), with an average of 1.64 × 10(-7) ± 8.01 × 10(-8); this value is 119 times lower than that of WMS. In addition, soil cleanup target levels (SCTLs) for both non-carcinogens (i.e., Phe, An, Fluo and Pyr) and carcinogens (i.e., B[a]A, Chry, B[b]F, B[k]F, B[a]P, Ind, D[a,h]A and B[g,h,i]P) in the KTS samples were estimated for all target groups, with an average value of 115,902 ± 197,229 ng g(-1).

Polycyclic aromatic hydrocarbons study in atmospheric fine and coarse particles using diagnostic ratios and receptor model in urban/industrial region

Atmospheric fine and coarse particles were collected in Teflon filters in three cities of the region of the Lower Sinos River Basin of Rio Grande do Sul in the year 2010. The filters were Soxhlet extracted, and 14 priority PAHs were analyzed using a gas chromatograph coupled to a mass spectrometer (GC/MS). The principal emission sources of these compounds were assessed by using diagnostic ratios and receptor model: positive matrix factorization (PMF 3.0) of the US Environmental Protection Agency. The results of PAHs concentration for the studied year showed significant levels of high molecular weight (HMW) PAH, Ind, and BghiP, in PM2.5 in the winter season, showing the influence of mobile sources. The application of receptor model PMF 3.0 revealed that the main sources of PAHs were vehicle fleet (both diesel and gasoline), followed by coal combustion, wood combustion, and resuspension of dust. The results of the receptor modeling are in agreement with the data obtained by the ratio diagnostic.

Comparison of different methods for extraction of polycyclic aromatic hydrocarbons (PAHs) from Sicilian (Italy) coastal area sediments

This paper describes a work aimed at improving the conditions of an extraction method, coupling GC-MS determination, for the analysis without cleanup phase, of polycyclic aromatic hydrocarbons (PAHs) from sediment samples. The automatic Soxhlet extraction in warm mode (using Extraction System B-811 Standard, Büchi) has demonstrated advantages for automation, reduced extraction time, and lower solvent use than for conventional Soxhlet extraction. Under these conditions, the recoveries are very good as they resulted greater than 85% and, in most of the cases, near 100%. The repeatability is also satisfactory (relative standard deviation less than 15%). The detection limits are also acceptable and ranged from 0.001 to0.01 μg/kg dry weight. Fifty-four sediment samples were collected. The total concentration of the 17 compounds investigated, in samples of sediments collected from three Sicilian coastal areas, expressed as the sum of concentrations, varies from 99 to 11,557 μg/kg of dry matrix; concentrations of total PAHs in the sediments of Cala are two to three times higher than the other stations.

PAHs in the Chinese environment: levels, inventory mass, source and toxic potency assessment

This paper presents a systematic but preliminary study on the levels, inventory mass, emission sources and risk of exposure to PAHs in China by examining 14 polycyclic aromatic hydrocarbons (from the 16 priority PAHs listed by the U.S. EPA, excluding naphthalene and acenaphthylene) in four main environmental media (air, water, soil and sediment). The concentration of individual PAHs in the air, soil, freshwater, seawater, freshwater sediment and marine sediment of China was compared with the global concentration range (GCR) of PAHs from a large number of studies. The PAH levels were found at the high end of the GCR in the air, at the upper middle of the GCR in the water body, and at the middle of the GCR in the soil and sediment. These indicate that PAHs still are emitted heavily in China. About 530 000 tons of Σ14PAH was estimated to be distributed into these four media in China. Soil possesses the highest proportion of the PAHs (60%), and the air has the lowest proportion (<0.5%). Therefore, the soil and sediment play an important role in the storage of PAHs. More than 10 thousand tons of PAHs are emitted from all kinds of sources. Firewood, straw, domestic and coking were considered as the main emissions of PAHs in the energy supply. A benzo[a]pyrene (BaP) based hazard quotient (HQ) was introduced to assess the potential toxic risk of exposure. The terrestrial water environment was found to have a high BaP exposure. The HQ value was more than 1 for 58% of freshwater and 39% of freshwater sediment samples. Urban and developed sites were considered to have high BaP exposure risk.

Preliminary characterization of polycyclic aromatic hydrocarbons, nitrated polycyclic aromatic hydrocarbons and polychlorinated dibenzo-p-dioxins and furans in atmospheric PM10 of an urban and a remote area of Chile

The composition of particulate organic fraction was determined in atmospheric aerosols emitted in two sites of central and southern Chile. In particular, polycyclic aromatic hydrocarbons (PAHs), nitrated-PAHs (N-PAHs) and polychlorinated dibenzo-p-dioxins (PCDDs) and furans (PCDFs) were investigated in both the urban site of Concepcion and the remote site of Coyhaique. The sampling was carried out with an active device during March and April 2007, and organic compounds adsorbed in air particles, having an aerodynamic diameter lower than 10 microm (PM10), were characterized using gas chromatography coupled with mass spectrometric detection (GC-MS). Aerosol contents varied from 0.004 to 3.4 ng m(-3) for PAH, from 0.007 to 3.5 pg m(-3) for N-PAH, from 0.002 to 355.7 fg Nm(-3) for PCDDs and from 0.04 to 15 fg Nm(-3) for PCDFs. As expected, the lowest values were found in the remote area. In Concepcion city, despite the low number of samples, PAH levels and diagnostic ratios of some marker compounds suggested the diesel emissions, probably coming from trucks, as the major source of particulate organic pollutants associated with direct emission. Another important source of atmospheric pollution in the urban site was likely represented by the steel industry existing in this area, outlined both by the analysis of PAH and PCDD/F levels. In the samples collected in the remote air of Coyhaique (located in the southern part of Chile), the concentration of pollutants characterized by a long lifetime, as PCDD/Fs, could be related to long-range transport phenomena, instead of local sources.

PAH diagnostic ratios for the identification of pollution emission sources

Polycyclic aromatic hydrocarbon (PAH) diagnostic ratios have recently come into common use as a tool for identifying and assessing pollution emission sources. Some diagnostic ratios are based on parent PAHs, others on the proportions of alkyl-substituted to non-substituted molecules. The ratios are applicable to PAHs determined in different environmental media: air (gas + particle phase), water, sediment, soil, as well as biomonitor organisms such as leaves or coniferous needles, and mussels. These ratios distinguish PAH pollution originating from petroleum products, petroleum combustion and biomass or coal burning. The compounds involved in each ratio have the same molar mass, so it is assumed they have similar physicochemical properties. Numerous studies show that diagnostic ratios change in value to different extents during phase transfers and environmental degradation. The paper reviews applications of diagnostic ratios, comments on their use and specifies their limitations.

Influence of urban activities on polycyclic aromatic hydrocarbons in precipitation: distribution, sources and depositional flux in a developing metropolis, Fortaleza, Brazil

We measured polycyclic aromatic hydrocarbons (PAHs) in bulk precipitation in the Fortaleza metropolitan area, Ceará, Brazil, for the first time. Because little information is available concerning PAHs in tropical climatic regions, we assessed their spatial distribution and possible sources and the influence of urban activities on the depositional fluxes of PAHs in bulk precipitation. The concentrations of individual and total PAHs (Σ(PAHs)) in bulk precipitation ranged from undetectable to 133.9 ng.L(-1) and from 202.6 to 674.8 ng.L(-1), respectively. The plume of highest concentrations was most intense in a zone with heavy automobile traffic and favorable topography for the concentration of emitted pollutants. The depositional fluxes of PAHs in bulk precipitation calculated in this study (undetectable to 0.87 μg.m(-2).month(-1)) are 4 to 27 times smaller than those reported from tourist sites and industrial and urban areas in the Northern Hemisphere. Diagnostic ratio analyses of PAH samples showed that the major source of emissions is gasoline exhaust, with a small percentage originating from diesel fuel. Contributions from coal and wood combustion were also found. Major economic activities appear to contribute to pollutant emissions.

Desenvolvimento e aplicação de método GC-MS/MS para análise simultânea de 17 HPAs em material particulado atmosférico

Os hidrocarbonetos policíclicos aromáticos (HPAs) estão associados ao aumento da incidência de diversos tipos de cânceres no homem. Essas moléculas são formadas principalmente na queima incompleta de matéria orgânica, sendo encontradas em todos os compartimentos ambientais. Órgãos regulamentadores das áreas ambiental e de saúde ocupacional consideram 17 HPAs como contaminantes atmosféricos prioritários. Este trabalho apresenta um método para análise simultânea destes HPAs utilizando-se a cromatografia a gás acoplada à espectrometria de massas operando no modo tandem (GC-MS/MS). Os limites de detecção e quantificação do método mostraram-se até 5 vezes inferiores aos obtidos no método GC-MS (SCAN). O método mostrou-se seletivo para análise de HPAs em extratos de amostras de material particulado atmosférico. Uma análise comparativa de dois sistemas de solventes (diclorometano/metanol 4:1 v/v e hexano/acetona 1:1 v/v) para a extração de HPAs, utilizando amostras de material particulado atmosférico, revelou que ambas as misturas de solventes possuem poder de extração semelhante. Os resultados sugerem que é possível realizar extração de HPAs de material particulado atmosférico em ultra-som com a mistura hexano/acetona (1:1), que é menos tóxica em relação à mistura diclorometano/metanol (4:1), bastante utilizada nestas análises, sem perdas significativas na exatidão do método.

Multifactorial optimization approach for the determination of polycyclic aromatic hydrocarbons in river sediments by gas chromatography-quadrupole ion trap selected ion storage mass spectrometry

A procedure for the determination of very low polycyclic aromatic hydrocarbons (PAHs) concentrations in sediment samples has been developed by gas chromatography-quadrupole ion trap mass spectrometry (GC-QIT MS) after extraction with dichloromethane and purification by using silica gel cleanup. Identification and quantification of analytes were based on the selected ion storage (SIS) strategy using deuterated PAHs as internal standards. In order to search out the main factors affecting the SIS mass spectrometry efficiency, four MS parameters, including target total ion count (TTIC), waveform amplitude (WA), transfer line (XLT) and ion trap temperatures (ITT) were subjected to a complete multifactorial design. The most relevant parameters obtained (TTIC and WA) were optimized by a rotatable and orthogonal composite design. Optimum values for these parameters were selected for the development of the method involving PAH determination in sediment samples. The optimized method exhibited a range of 111-760% higher signal-to-noise (S/N) ratios for PAHs in comparison with the method operated by the default conditions, demonstrating that the multifactorial optimization contributed to substantially improve the sensitivity of the GC-QIT MS determination. The accuracy of the method was verified by analyzing NWRI EC-3 certified reference material (Lake Ontario sediment). The selectivity, sensitivity (limits of quantification were in the range of 0.02-11.0 ng g(-1)), accuracy (recoveries >or=77%) and precision (RSD<or=30%) obtained were quite adequate for the determination of very low target PAHs in sediment samples. The established method was then applied to determine 16 PAHs in river sediments from the Metropolitan Region of Curitiba, Brazil. Two selected sediment samples were analyzed, one from the Canguiri River (a slightly urbanized area), and the other from the Iguaçu River (a heavily urbanized area), illustrating the capabilities of the method to detect PAHs at the threshold concentrations necessary to classify the sediments as well as the status of contamination.