An analytical method coupling accelerated solvent extraction and HPLC-fluorescence for the quantification of particle-bound PAHs in indoor air sampled with a 3-stages cascade impactor

Employing a magnetic chitosan/molybdenum disulfide nanocomposite for efficiently removing polycyclic aromatic hydrocarbons from milk samples

This study aimed to develop a highly efficient nanocomposite composed of magnetic chitosan/molybdenum disulfide (CS/MoS2/Fe3O4) for the removal of three polycyclic aromatic hydrocarbons (PAHs)-pyrene, anthracene, and phenanthrene. Novelty was introduced through the innovative synthesis procedure and the utilization of magnetic properties for enhanced adsorption capabilities. Additionally, the greenness of chitosan as a sorbent component was emphasized, highlighting its biodegradability and low environmental impact compared to traditional sorbents. Factors influencing PAH adsorption, such as nanocomposite dosage, initial PAH concentration, pH, and contact time, were systematically investigated and optimized. The results revealed that optimal removal efficiencies were attained at an initial PAH concentration of 150 mg/L, a sorbent dose of 0.045 g, pH 6.0, and a contact time of 150 min. The pseudo-second-order kinetic model exhibited superior fitting to the experimental data, indicating an equilibrium time of approximately 150 min. Moreover, the equilibrium adsorption process followed the Freundlich isotherm model, with kf and n values exceeding 7.91 mg/g and 1.20, respectively. Remarkably, the maximum absorption capacities for phenanthrene, anthracene, and pyrene on the sorbent were determined as 217 mg/g, 204 mg/g, and 222 mg/g, respectively. These findings underscore the significant potential of the CS/MoS2/Fe3O4 nanocomposite for efficiently removing PAHs from milk and other dairy products, thereby contributing to improved food safety and public health.

Raman spectroscopy combined with partial least squares (PLS) based on hybrid spectral preprocessing and backward interval PLS (biPLS) for quantitative analysis of four PAHs in oil sludge

Polycyclic aromatic hydrocarbons (PAHs) contained in a large amount of oily sludge produced in petroleum and petrochemical production has become one of the main environmental protection concerns in the industry. The accurate determination of PAHs is of great significance in the field of petroleum geochemistry and environmental protection. In this study, Raman spectroscopy combined with partial least squares (PLS) based on different hybrid spectral preprocessing methods and variable selection strategies was proposed for quantitative analysis of phenanthrene, fluoranthrene, fluorene and naphthalene (Phe, Flt, Flu and Nap) in oil sludge. At first, PAHs in oily sludge was extracted by solid-liquid extraction with methanol as extractant, and Raman spectra of 21 oily sludge samples were collected by portable Raman spectrometer. And then, the influence of first derivative (D1st), wavelet transform (WT) and their hybrid spectral preprocessing on the predictive performance of the PLS calibration model was discussed. Thirdly, biPLS (backward interval partial least squares) was used to optimize the input variables before and after the hybrid spectral preprocessing methods, and the influence of biPLS and the hybrid spectral preprocessing sequence on the predictive performance of the PLS calibration model was discussed. Finally, the predictive performance of the PLS calibration model was optimized according to the results of leave-one-out cross-validation (LOOCV) method. The results show that the biPLS-D1st-WT-PLS calibration model established by using biPLS first to select the characteristic variables, followed by hybrid spectral preprocessing of the characteristic variables, has better prediction performance for Flt (determination coefficient of prediction (R2P) = 0.9987, and the mean relative error of prediction (MREP) = 0.0606). For Phe, Flu and Nap, the WT-biPLS-PLS calibration model has a better predictive effect (R2P are 0.9995, 0.9996 and 0.9983, and MREP are 0.0426, 0.0719 and 0.0497, respectively). In general, portable Raman spectroscopy combined with PLS calibration model based on different hybrid spectral preprocessing and variable selection strategies has achieved good prediction results for quantitative analysis of four PAHs in oily sludge. It is a new strategy to firstly select the characteristic variables of the original spectra, and secondly to preprocess the characteristic variables by the hybrid spectral preprocessing, which will provide a new idea for the establishment of quantitative analysis methods for PAHs in oily sludge.

Thermal desorption gas chromatography-mass spectrometric analysis of polycyclic aromatic hydrocarbons in atmospheric fine particulate matter

Thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) is used to analyze polycyclic aromatic hydrocarbons (PAHs) in atmospheric fine particulate matter. However, despite the high sensitivity of TD-GC-MS, the recovery rate of PAHs is greatly influenced by active sites in the equipment. PAHs are decomposed or adsorbed at active sites, decreasing quantitative accuracy. Also, the thermal extraction of PAHs is easily affected by the matrix in PM2.5 samples, decreasing the thermal extraction efficiency. Herein, the analytical sensitivities of PAHs were improved by adding analyte protectant (AP) and thermal desorption aid (TDA) as an auxiliary agent. The combination of 2 µL of 0.5 w/v% D-sorbitol (as AP) and 2 µL of 10 w/v% Tween®20 (as TDA) was found to be most effective in improving the analytical sensitivity of PAHs. The sensitivities of 5-6-ring PAHs with high boiling points increased most when analyzing blank filter papers added with PAHs standard sample or real samples of PM2.5 compared with the samples without the auxiliary agent. When analyzing real samples of PM2.5, the peak areas of 5-ring and 6-ring PAHs in the PM2.5 sample added with the optimized auxiliary agent were 1.40 and 1.96 times that without the auxiliary agent. It is considered that AP in the auxiliary agent covered active sites and protected PAHs undergoing decomposition or adsorption. TDA improved the thermal extraction rate of high boiling point PAHs. When using alternative heat sampling equipment to analyze low concentrations of high boiling point components, the auxiliary agent proposed herein can increase the analytical sensitivity toward the target compounds.

Quantitative analysis of polycyclic aromatic hydrocarbons in soil by infrared spectroscopy combined with hybrid variable selection strategy and partial least squares

Infrared spectroscopy (IR) combined with multivariate calibration technology can be used as a potential method to quantitative analysis of polycyclic aromatic hydrocarbons (PAHs) in soil, which provides a rapid data support for soil risk assessment. However, IR spectrum contains lots of useless information, its predictive performance is poor. Variable selection is an effective strategy to eliminate irrelevant wavelengths and enhance predictive performance. In this study, IR combined with partial least squares (PLS) was proposed to quantify anthracene and fluoranthene in soil. In order to improve the predictive performance of the PLS calibration model, the synergy interval PLS (siPLS) method was first used for "rough selection" to select feature bands; on this basis, "fine selection" was performed to extract the feature variables. In "fine selection", three different feature variables selection methods, such as successive projection algorithm (SPA), genetic algorithm (GA), and particle swarm optimization (PSO), were compared for their performance in extracting effective variables. The results show that the siPLS-GA calibration model receive a lowest root mean square error (RMSE) and a largest determination coefficient (R²). Results of external validation demonstrate an excellent predictive performance of siPLS-GA calibration model, with the R² = 0.9830, RMSE = 0.5897 mg/g and R² = 0.9849, RMSE = 0.4739 mg/g for anthracene and fluoranthene, respectively. In summary, siPLS combined with GA can accurately extract the effective information of the target substance and improve the predictive performance of the PLS calibration model based on IR spectroscopy.

Estimation of human exposure to polycyclic aromatic hydrocarbons (PAHs) based on the dietary and outdoor atmospheric monitoring in the Czech Republic

In everyday life, humans can be exposed to various chemicals including ubiquitous polycyclic aromatic hydrocarbons (PAHs) mostly through food consumption and/or inhalation. In the presented study, we evaluated PAH concentrations in duplicate samples (n = 251). Concurrently, the outdoor concentrations of PM2.5-bound PAHs in filters (n = 179) were also monitored. The daily exposure to PAHs was subsequently estimated for the risk group of pregnant women living in two different cities (Most city and Ceske Budejovice city) in the Czech Republic. This is the first unique study in Europe to evaluate human daily exposure to 20 PAHs both from inhalation (outdoor air) and dietary intake. For the analysis of samples collected during the years 2016/2017, a gas chromatography coupled to tandem mass spectrometry was applied. Focusing on the diet samples, a slightly higher sum of detected PAHs was measured in duplicates obtained from the mothers living in the Most city (0.115-186 ng g^-1) compared to the Ceske Budejovice city (0.115-97.1 ng g^-1). This could be due to a higher occurrence of major analytes (pyrene, phenanthrene and fluoranthene) and the different composition of daily diet. The values of toxic and most often detected substance, namely benzo[a]pyrene (BaP), were also higher by 35% in the Most city. Regarding the outdoor air contamination (only particulate phase - PM2.5 was assessed), here the opposite situation was observed, relatively higher amounts of all PAHs were monitored in the Ceske Budejovice city (median: 2.22 ng m^-3) than in the Most city (median: 1.07 ng m^-3). These higher PAH concentrations in the Ceske Budejovice city are probably caused by more intense traffic, higher population and also by the occurrence of old-fashioned heating plant. Depending on a seasonal variability, especially during the cold season, the concentrations of BaP exceeded the European average emission limit (1 ng m^-3) by 1.5-6 times. This highest inhalation exposure to all PAHs was observed in February. However, the dietary intake still represents the dominant contributor (>90%) to the total PAH exposure.

Different biological effects of PM2.5 from coal combustion, gasoline exhaust and urban ambient air relate to the PAH/metal compositions

Few studies have compared the biological effects of PM_2.5 from coal combustion, gasoline exhaust and urban ambient air, and the roles of polycyclic aromatic hydrocarbons (PAHs) and metals playing in the process remain unclear. In this study, PM_2.5 samples from coal combustion, gasoline exhaust and urban ambient air were analyzed for 16 PAHs and 23 metals. Cytotoxic and inflammatory effects of different PM_2.5 were evaluated on differentiated THP-1 and A549 cells, respectively. We found that the coal combustion PM_2.5 samples induced stronger cytotoxic and inflammatory effects (p < 0.05). Pearson's correlation and principal component analysis showed that the PAHs containing four or more benzenoid rings and specific metals of cadmium, thallium, zinc and lead were positively related to the biological effects. Our results suggested that coal combustion PM_2.5 might be a more serious health hazard. Specific PAHs and metals might be account for the PM_2.5 induced biological effects.

Environmental and lifestyle factors affecting exposure to polycyclic aromatic hydrocarbons in the general population in a Middle Eastern area

The aim of this study was to investigate environmental and lifestyle factors affecting exposure to PAHs in the general population in a large city of the Middle East (Tehran) by measuring urinary monohydroxy polycyclic aromatic hydrocarbons (OH-PAHs) and establishing relationships between PAHs exposure and related factors. Urine samples were collected from 222 randomly chosen subjects who were living in the urban area of Tehran, Iran. Subjects were required to complete a detailed questionnaire aimed to document their personal and sociodemographic information, activities, cooking-related appliances, smoking history/exposure, and consumed foodstuff. Identification and quantification of six OH-PAHs was carried out using a gas chromatography with mass spectrometry (GC-MS). The geometric means for 1-OHP, 1-NAP, 2-NAP, 2-FLU, 9-FLU, and 9-PHE for whole population study were 310, 1220, 3070, 530, 330, and 130 ng/g creatinine, respectively. The two naphthalene metabolites contributed on average 77% of the total concentration of six measured OH-PAHs, followed by the 2-FLU, 1-OHP, 9-FLU, and 9-PHE. The most important predictors of urinary PAHs were consumption of grilled/barbecued foods, smoking, and exposure to environmental tobacco smoking. Water pipe smoking was linked to urinary OH-PAH metabolite in a dose-response function. Residential traffic was also related with OH-PAH metabolite concentrations. Other factors including gender, age, exposure to common house insecticides, open burning, and candle burning were found to be statistically associated with the urinary levels of some OH-PAHs. High exposure to PAHs among general population in Middle Eastern large cities and its associated health implications calls for public health measures to reduce PAHs exposure.

Association of atmospheric concentrations of polycyclic aromatic hydrocarbons with their urinary metabolites in children and adolescents

This study aims to determine the atmospheric concentrations of particulate matter 2.5 (PM_2.5)-bounded polycyclic aromatic hydrocarbons (PAHs) and their association with their urinary metabolites in children and adolescents. This study was conducted from October 2014 to March 2016 in Isfahan, Iran. We measured 16 species of PAHs bounded to PM_2.5 by gas chromatography mass spectrometry (GC/MS) from 7 parts of the city. Moreover, PAH urinary metabolites were measured in 186 children and adolescents, randomly selected from households. Urinary metabolites consisted of 1-hydroxy naphthalene (1-naphthol), 2-hydroxy naphthalene (2-naphthol), 9-hydroxy phenanthrene (9-phenanthrol), and 1-hydroxy pyrene using GC/MS. Considering the short half-lives of PAHs, we measured the metabolites twice with 4 to 6 months of time interval. We found that the ambient concentrations of PAHs were significantly associated with their urinary metabolites. 1-hydroxy naphthalene and 2-hydroxy naphthalene concentrations showed an increase of 1.049 (95% CI: 1.030, 1.069) and 1.047 (95% CI: 1.025, 1.066) for each unit increase (1 ng/m³) in ambient naphthalene. Similarly, 1-hydroxy pyrene showed an increase of 1.009 (95% CI: 1.006-1.011) for each unit increase (1 ng/m³) in ambient pyrene concentration after adjustment for body mass index, physical activity level, urinary creatinine, age, and sex. The association of urinary 9-hydroxyphenanthrene and ambient phenantherene was significant in the crude model; however after adjustment for the abovementioned covariates, it was no more significant. We found significant correlations between exposure to ambient PM_2.5-bounded PAHs and their urinary excretion. Considering the adverse health effects of PAHs in the pediatric age group, biomonitoring of PAHs should be underscored; preventive measures need to be intensified.

Polydopamine-reinforced magnetization of zeolitic imidazolate framework ZIF-7 for magnetic solid-phase extraction of polycyclic aromatic hydrocarbons from the air-water environment

Zeolitic imidazolate frameworks (ZIFs) consist of metal nodes connected to imidazolate linkers, having both the properties of metal-organic frameworks (MOFs) and inorganic zeolites, such as controllable pore sizes, high porosity and surface areas, as well as exceptional thermal and chemical stability, thereby making them a class of attractive materials for diverse analytical applications. In this study, we reported a facile magnetization process of ZIF-7 (zinc benzimidazolate) for simultaneous magnetic extraction of polycyclic aromatic hydrocarbons (PAHs) by simply mixing ZIF-7 and polydopamine (PDA)-coated Fe3O4 nanoparticles (PDA@Fe3O4) in solutions. Functional groups (-OH and -NH2), provided by PDA as a highly efficient molecular linker, could attract and anchor ZIF-7 through noncovalent adsorption and covalent cross-link interactions, thereby promoting the complete magnetization of ZIFs and enhancing their stability and reusability. The bridging ligand benzimidazolate, could be bonded with PAHs because of its high surface area, large pores, accessible coordinative unsaturated sites (π-complexation), and π-π stacking action. This ZIF-based magnetic solid-phase extraction (SPE), coupled with gas chromatography/tandem mass spectrometry (GC/MS), was further evaluated for analysis of PAHs from rainwater and air samples of particulate matter less than 2.5μm in diameter (PM2.5). The main effective parameters, including ionic strength, solution pH, extraction time, desorption solvent and desorption time, were investigated, respectively. Under optimized conditions, the developed method based on Fe3O4@PDA/ZIF-7 gave detection limits of 0.71-5.79ng/L, and quantification limits of 2.50-19.2ng/L for PAHs, respectively. The relative standard deviations for intra-day and inter-day analyses were in the range of 3.1-9.1% and 6.1-12.7%, respectively. The PAHs founded in PM2.5 were in the range of 0.40-6.79ng/m(3). Good recoveries (>82%) with low relative standard deviations (≤9.2%) were achieved. This method was demonstrated to be an accurate, convenient and sensitive pretreatment procedure for trace analysis of environmental water and air samples.

Characterization and risk assessment of polycyclic aromatic hydrocarbons (PAHs) in urban atmospheric Particulate of Tehran, Iran

In this study, atmospheric concentrations of particulate-bound polycyclic aromatic hydrocarbons (PAHs) in Tehran megacity were determined to investigate the concentration, distribution, and sources of PAHs in PM10. The health risk from exposure to airborne BaPeq through inhalation pathway was also assessed. Toxic equivalency factors (TEFs) approach was used for quantitative risk estimate, and incremental lifetime cancer risk (ILCR) was calculated. PM10 samples were collected at ten sampling locations during the summer 2013 and winter 2014 by using two independent methods of field sampling. The PM10 concentration in winter (89.55 ± 15.56 μg m(-3)) was 1.19 times higher than that in summer (75.42 ± 14.93 μg m(-3)). Sixteen PAHs were measured with the total average concentrations of PAHs ranged from 56.98 ± 15.91 to 110.35 ± 57.31 ng m(-3) in summer and from 125.87 ± 79.02 to 171.25 ± 73.94 ng m(-3) in winter which were much higher than concentrations measured in most similar studies conducted around the world. Molecular diagnostic ratios were used to identify PAH emission sources. The results indicated that gasoline-driven vehicles are the major sources of PAHs in the study area. Risk analysis showed that the mean and 90 % probability estimated inhalation ILCRs were 7.85 × 10(-6) and 16.78 × 10(-6), respectively. Results of a sensitivity analysis indicated that BaP concentration and cancer slope factor (CSF) contributed most to effect on ILCR mean.