Volatile Organic Contaminants Research Articles

Vapor-phase transport of per and polyfluoroalkyl substances: Processes, modeling, and implications

An increasing number of studies have demonstrated the presence of per and polyfluoroalkyl substances (PFAS) in the vapor phase. It is therefore important to consider the potential for vapor-phase transport of PFAS in soil and the vadose zone and to investigate the processes impacting the retention and transport of volatile PFAS in soil. It is also critically important to evaluate existing models and develop new models as needed for their application to PFAS vapor-phase transport. The objectives of the present work were to provide an overview of vapor-phase transport processes and modeling, with a specific focus on their relevance for PFAS, and to discuss implications for mass discharge to groundwater, vapor intrusion, and soil vapor extraction. Decades of research have been devoted to the retention and transport of legacy volatile organic contaminants in the vadose zone. This work provides an abundant source of information concerning the many factors and processes of relevance, and insights into the development and application of mathematical modeling. However, given the unique properties of PFAS, there is a need to conduct research to investigate vapor-phase transport of PFAS and to develop PFAS-specific models. We highlight with illustrative examples that vapor-phase transport can be significantly more rapid than aqueous-phase advective transport, which can result in enhanced mass discharge to groundwater.

Volatile organic contaminants in HDPE milk bottles along the mechanical recycling value chain, revealing origins and contamination pathways

To progress towards closed-loop recycling of plastic packages it is vital to understand the origin of contaminants and to develop effective mitigation strategies. High density polyethylene (HDPE) milk bottles were sampled at nine different locations along the recycling value chain and analysed with two gas chromatography – mass spectroscopy methods to study the presence of volatile organic compounds. The total approximated concentration of volatiles reduced over time from the production of the bottles up to the cross-docking facility for the separately collected lightweight packaging waste (from about 250 to 100 ppm), as alkanes and alkenes evaporate from the bottle. A clear maximum was observed in the number of identified of volatiles and in the total approximated concentration in milk bottles at the sorted HDPE product. Here contaminants peaked that originate from the milk, from other packaging components (labels, caps, inlays), from other packages and from the surrounding atmosphere. When only the milk bottles were manually separated out from this sorted product and these were mechanically recycled, flakes were obtained that contain the least amount of volatile compounds, much less than the freshly produced bottles (about 25–50 ppm). The type of volatiles present was, however, markedly different. In the freshly produced bottles alkanes, alkenes and intentionally added anti-oxidant were found, whereas in the recycled flakes mostly contaminants were found that originated from: the milk, the other packaging components, other packages and the surrounding atmosphere. Seven different contamination pathways were discerned. The gathered knowledge facilitates the future development of food-grade recycled HDPE.

Feasibility of compacted attapulgite/diatomite amended clayey soils as gas barrier materials

Compacted clay liners are extensively used as barriers to control the upward diffusion of vapors of volatile or semi-volatile organic contaminants released from unsaturated contaminated soils at industry-contaminated sites. This study aimed to investigate the gas diffusion barrier performance of compacted clayey soils amended with three agents including attapulgite and diatomite individually, and attapulgite/diatomite mixture. The properties including water retention, volumetric shrinkage, gas diffusion, and unconfined compressive strength were evaluated through a series of laboratory tests of amended compacted clayey soils. The results demonstrate that the decrease in volume proportions of inter-aggregate pores leads to an increase in unconfined compressive strength (qu). Both hydrophilic groups and microstructures of attapulgite and diatomite result in an increase in water retention percent (Wt) of compacted clayey soil specimens after amendment regardless of the type of agent or initial water content (w0). Furthermore, the ratio of the gas diffusion coefficient (De) to the gas diffusion coefficient in the air (Da) was significantly reduced owing to a decrease in volume proportions of inter-aggregate pores, hydrophilic group, and microstructures of attapulgite and diatomite. Scanning electron microscope analyses revealed that rod-shaped attapulgite filled the inter-aggregate pores formed by clay particles, whereas the disc-shaped diatomite particles, characterized by micropores, failed to obstruct the inter-aggregate pores due to their larger particle size. Mercury intrusion porosimetry (MIP) analyses showed a reduction in pore volume in the inter-aggregate pores, leading to a reduction in the total pore volume for both the attapulgite and attapulgite/diatomite mixture amended clays, which is in accordance with the scanning electron microscope (SEM) results. The findings are pertinent to the practical application of compacted clay liners as gas barriers against the upward migration of volatile or semi-volatile organic contaminants at contaminated sites.

Dispersive liquid-liquid microextraction as a novel enrichment approach for compound-specific carbon isotope analysis of chlorinated phenols.

Compound-specific isotope analysis (CSIA) via gas chromatography-isotope ratio mass spectrometry (GC-IRMS) is a potent tool to elucidate the fate of (semi-)volatile organic contaminants in technical and environmental systems. Yet, due to the comparatively low sensitivity of IRMS, an enrichment step prior to analysis often is inevitable. A promising approach for fast as well as economic analyte extraction and preconcentration prior to CSIA is dispersive liquid-liquid microextraction (DLLME) - a well-established technique in concentration analysis of contaminants from aqueous samples. Here, we present and evaluate the first DLLME method for GC-IRMS exemplified by the analysis of chlorinated phenols (4-chlorophenol, 2,4-dichlorophenol, and 2,4,6-trichlorophenol) as model compounds. The analytes were simultaneously acetylated with acetic anhydride and extracted from the aqueous phase using a binary solvent mixture of acetone and tetrachloroethylene. With this method, reproducible δ13C values were achieved with errors ≤ 0.6‰ (n = 3) for aqueous concentrations down to 100 μg L-1. With preconcentration factors between 130 and 220, the method outperformed conventional liquid-liquid extraction in terms of sample preparation time and resource consumption with comparable reproducibility. Furthermore, we have demonstrated the suitability of the method (i) for the extraction of the analytes from a spiked river water sample and (ii) to quantify kinetic carbon isotope effect for 2,4,6-trichlorophenol during reduction with zero-valent zinc in a laboratory batch experiment. The presented work shows for the first time the potential of DLLME for analyte enrichment prior to CSIA and paves the way for further developments, such as the extraction of other compounds or scaling up to larger sample volumes.

Substituent-Controlled Photophysical Responses in Dihydropyridine Derivatives and Their Application in the Detection of Volatile Organic Contaminants.

In the ever-expanding realm of organic fluorophores, structurally simple and synthetically straightforward molecules with unique photophysical properties have received special attention. Among these, 1,4-dihydropyridine (DHP) is an important scaffold that permits fine-tuning of their photophysical properties through substituents on the periphery. Herein, we describe a series of solid-emissive N-substituted 2,6-dimethyl-4-methylene-1,4-dihydropyridine derivatives appended with electron-withdrawing substituents (dicyanomethylene or 2-dicyanomethylene-3-cyano-2,5-dihydrofuran) at the C-4 position and alkyl or alkylaryl groups on the DHP nitrogen. Electronic and steric tuning exerted by these substituents resulted in interesting photophysical properties such as negative solvatochromism, solidstate, and aggregation-induced emission (AIE). Theoretical calculations were carried out to explain the solvatochromic properties. Insight into the AIE properties was obtained through variable-temperature nuclear magnetic resonance and viscosity- and temperature-dependent emission studies. The variations in molecular packing in the crystal lattice with changes in the N-substituents contributed to the tuning of solid state emission properties. Detection of aromatic volatile organic compounds (VOCs) was achieved using the aggregates of the DHP derivatives. Among the VOCs, p-xylene elicited a significant enhancement in emission, allowing its detection at submicromolar levels.

Thermal conductive heating coupled with in situ chemical oxidation for soil and groundwater remediation: A quantitative assessment for sustainability

Thermal conductive heating (TCH), broadly applied to remove volatile and semi-volatile organic contaminants from subsurface, is often considered unsustainable due to its high carbon emissions, energy consumption and expensive costs. TCH coupled with in situ chemical oxidation (TCH-ISCO) has drawn much attention recently due to its ability to achieve cleanup goals of groundwater remediation in a timely manner as TCH does, but at much lower temperatures. However, there is a lack of quantitative assessment on the sustainability of TCH-ISCO based on field data. In this study, a quantitative life cycle assessment approach coupled with best management practices (LCA-BMPs) model was developed with data collected in the field to assess the sustainability of TCH-ISCO for chlorinated aliphatic hydrocarbons (CAHs) contaminated soil and groundwater remediation for the first time. The results revealed that the energy supply via electricity contributed to 68% and 93% of the adverse environmental impacts (e.g., global warming, mineral resource scarcity, and fine particulate matter formation), for TCH-ISCO and TCH, respectively. In addition, the carbon emissions and direct cost of TCH-ISCO were estimated to be 80% and 70% less than TCH, respectively. With regard to the social sustainability, TCH slightly outperformed TCH-ISCO. The overall sustainability scores of TCH-ISCO and TCH were 89.6 and 61.9, respectively, demonstrating that the sustainability performance of TCH-ISCO was significantly better than that of TCH. In view of the current demand for sustainable remediation technology, this study provides reliable data evaluation for the application of TCH-ISCO.

Low-dose inhalation exposure to trichloroethylene induces dopaminergic neurodegeneration in rodents.

Trichloroethylene (TCE) is one of the most pervasive environmental contaminants in the world and is associated with Parkinson disease (PD) risk. Experimental models in rodents show that TCE is selectively toxic to dopaminergic neurons at high doses of ingestion, however, TCE is a highly volatile toxicant, and the primary pathway of human exposure is inhalation. As TCE is a highly lipophilic, volatile organic compound (VOC), inhalation exposure results in rapid diffusion throughout the brain, avoiding first-pass hepatic metabolism that necessitated high doses to recapitulate exposure conditions observed in human populations. We hypothesized that inhalation of TCE would induce significantly more potent neurodegeneration than ingestion and better recapitulate environmental conditions of vapor intrusion or off gassing from liquid TCE. To this end, we developed a novel, whole-body passive exposure inhalation chamber in which we exposed 10-month-old male and female Lewis rats to 50 ppm TCE (time weighted average, TWA) or filtered room air (control) over 8 weeks. In addition, we exposed 12-month-old male and female C57Bl/6 mice to 100 ppm TCE (TWA) or control over 12 weeks. Both rats and mice exposed to chronic TCE inhalation showed significant degeneration of nigrostriatal dopaminergic neurons as well as motor and gait impairments. TCE exposure also induced accumulation of pSer129-αSyn in dopaminergic neurons as well as microglial activation within the substantia nigra of rats. Collectively, these data indicate that TCE inhalation causes highly potent dopaminergic neurodegeneration and recapitulates some of the observed neuropathology associated with PD, providing a future platform for insight into the mechanisms and environmental conditions that influence PD risk from TCE exposure.

Effects of Corsi-Rosenthal boxes on indoor air contaminants: non-targeted analysis using high resolution mass spectrometry.

In response to COVID-19, attention was drawn to indoor air quality and interventions to mitigate airborne COVID-19 transmission. Of developed interventions, Corsi-Rosenthal (CR) boxes, a do-it-yourself indoor air filter, may have potential co-benefits of reducing indoor air contaminant levels. We employed non-targeted and suspect screening analysis (NTA and SSA) to detect and identify volatile and semi-volatile organic contaminants (VOCs and SVOCs) that decreased in indoor air following installation of CR boxes. Using a natural experiment, we sampled indoor air before and during installation of CR boxes in 17 rooms inside an occupied office building. We measured VOCs and SVOCs using gas chromatography (GC)high resolution mass spectrometry (HRMS) with electron ionization (EI) and liquid chromatography (LC) HRMS in negative and positive electrospray ionization (ESI). We examined area count changes during vs. before operation of the CR boxes using linear mixed models. Transformed (log2) area counts of 71 features significantly decreased by 50-100% after CR boxes were installed (False Discovery Rate (FDR) p-value < 0.2). Of the significantly decreased features, four chemicals were identified with Level 1 confidence, 45 were putatively identified with Level 2-4 confidence, and 22 could not be identified (Level 5). Identified and putatively identified features (Level ≥4) that declined included disinfectants (n = 1), fragrance and/or food chemicals (n = 9), nitrogen-containing heterocyclic compounds (n = 4), organophosphate esters (n = 1), polycyclic aromatic hydrocarbons (n = 8), polychlorinated biphenyls (n = 1), pesticides/herbicides/insecticides (n = 18), per- and polyfluorinated alkyl substances (n = 2), phthalates (n = 3), and plasticizers (n = 2). We used SSA and NTA to demonstrate that do-it-yourself Corsi-Rosenthal boxes are an effective means for improving indoor air quality by reducing a wide range of volatile and semi-volatile organic contaminants.

Photothermal-Photocatalytic CSG@ZFG Evaporator for Synergistic Salt Rejection and VOC Removal during Solar-Driven Water Distillation.

Sunlight-driven interfacial photothermal evaporation has been considered as a promising strategy for addressing global water crisis. Herein, we fabricated a self-floating porous triple-layer (CSG@ZFG) evaporator using porous fibrous carbon derived from Saccharum spontaneum (CS) as a photothermal material. The middle layer of the evaporator is composed of hydrophilic sodium alginate crosslinked by carboxymethyl cellulose and zinc ferrite (ZFG), whereas the top hydrophobic layer consists of fibrous (CS) integrated benzaldehyde-modified chitosan gel (CSG). Water is transported to the middle layer through the bottom elastic polyethylene foam using natural jute fiber. Such a strategically designed three-layered evaporator exhibits a broad-band light absorbance (96%), excellent hydrophobicity (120.5°), a high evaporation rate of 1.56 kg m-2 h-1, an energy efficiency of 86%, and outstanding salt mitigation ability under the simulated sunlight of intensity 1 sun. Adding ZnFe2O4 nanoparticle as a photocatalyst has been proved to be capable of restricting the evaporation of volatile organic contaminants (VOCs) like phenol, 4-nitrophenol, and nitrobenzene to ensure the purity of evaporated water. Such an innovatively designed evaporator offers a promising approach for the production of drinking water from wastewater and seawater.

Exploring the nonlinear partitioning mechanism of volatile organic contaminants between soil and soil vapor using machine learning

Traditional phase equilibrium models usually depend on simplified assumptions and empirical parameters, which are difficult to obtain during regular site investigations. As a result, they often under- or over-estimate soil vapor concentrations for assessing the risks of volatile organic compound (VOC)-contaminated sites. In this study, we develop several machine learning models to predict soil vapor concentrations using 2225 soil-soil vapor data pairs collected from seven contaminated sites in northern China. Compared to the classic dual equilibrium desorption model, the random forest (RF) model can provide more accurate predictions of soil vapor concentrations by at least 1–2 orders of magnitude. Among the employed covariates, soil concentration and organic carbon-water partition coefficient are two of the most significant explanatory covariates affecting soil vapor concentrations. Further examination of the developed RF model reveals the phase equilibrium behavior of VOCs in soil is that: the soil vapor concentration increases with soil concentration at different rates in the first two intervals but remains almost unchanged in the last interval; the solid-vapor partitioning interface may still exist at up to 15% mass water content in our simulations. These findings can help site investigators perform more accurate risk assessments at VOC-contaminated sites.

Discriminative Detection of Aliphatic, Electron‐Rich and Electron‐Deficient Aromatic Volatile Organic Contaminants Using Conjugated Polymeric Fluorescent Nanoaggregates with Aggregation Induced Emission Characteristics

AbstractDiscrimination of aromatic, aliphatic volatile organic compounds (VOCs) with high sensitivity and easy operational techniques is important due to related environmental implications. Herein the development of fluorescent conjugated polymers is reported, consisting of donor–acceptor pairs and their nanoaggregates as fluorophores with differential emission behavior in the presence of aromatic, aliphatic VOCs and electron‐deficient VOCs both in aqueous solution and solid state. The polymeric network consists of fluorene moiety with dangling alkyl groups as donors and aggregation‐induced emission (AIE) active tetraphenylethylene (TPE) unit as an acceptor. The corresponding fluorescent nanoaggregates exhibit enhancement in the emission intensity owing to restriction in intramolecular motion of AIE unit in the presence of aliphatic VOCs, whereas the fluorescence enhancement is accompanied by a bathochromic shift in emission maxima in the case of aromatic VOCs owing to the conformational change in the phenyl rings of TPE unit. On the other hand, the fluorescence of nanoaggregates quenches in the presence of an electron‐deficient VOC through a possible nonradiative electron transfer. Detailed mechanistic studies are corroborated through a variety of spectroscopic, density functional theory calculations, and theoretical simulations. The discriminatory response of the polymeric nanoaggregates toward a different kind of VOCs can also be observed visually in the thin‐film state.

Recent development of the fluorescence-based detection of volatile organic compounds: a mechanistic overview

This review explores the up-to-date development of fluorescence-based detection of volatile organic contaminants (VOCs) on multiple platforms mainly highlighting mechanistic prospect that could help the future structural design of smart VOC sensors.

Effects of Carbonate Minerals on Shale-Hydraulic Fracturing Fluid Interactions in the Marcellus Shale

Natural gas extracted from tight shale formations, such as the Marcellus Shale, represents a significant and developing front in energy exploration. By fracturing these formations using pressurized fracturing fluid, previously unobtainable hydrocarbon reserves may be tapped. While pursuing this resource, hydraulic fracturing operations leave chemically complex fluids in the shale formation for at least two weeks. This provides a substantial opportunity for the hydraulic fracturing fluid (HFF) to react with the shale formation at reservoir temperature and pressure. In this study, we investigated the effects of the carbonates on shale-HFF reactions with a focus on the Marcellus Shale. We performed autoclave experiments at high temperature and pressure reservoir conditions using a carbonate-rich and a decarbonated or carbonate-free version of the same shale sample. We observed that carbonate minerals buffer the pH of the solution, which in turn prevents clay dissolution. Carbonate and bicarbonate ions also scavenge reactive oxidizing species (ROS), which prevents oxidation of shale organic matter and volatile organic compounds (VOCs). Carbonate-free samples also show higher pyrite dissolution compared to the carbonate-rich sample due to chelation reactions. This study demonstrates how carbonate minerals (keeping all other variables constant) affect shale-HFF reactions that can potentially impact porosity, microfracture integrity, and the release of heavy metals and volatile organic contaminants in the produced water.

Cu2O-TiO2 Composite for Photocatalytic Degradation of Benzene and its Derivatives Using Visible Light

Background: Heterostructured nanocomposites have gained massive attention for their catalytic properties lately. A wide array of different visible-light-active photocatalysts (VLAPs) have been extensively studied over the past couple of years to fine-tune the bandgap of various stable semiconductors. Objective: The current investigation reports the sensitization of TiO2 nanoparticles with nano-sized cuprous oxide, a well-studied p-type semiconductor, which has a relatively narrow bandgap ranging between 2.1 eV &amp; 2.6 eV, to obtain a visible light active photocatalyst. Methods: Visible-light-active Cu2O–TiO2 nanocomposite was synthesized using solvothermal technique. The nanocomposite’s structure and size properties were studied using powder diffraction (XRD), and electron microscopy (FESEM and HRTEM). Cu2O-TiO2 nanocomposite was tested on benzene, toluene and chlorobenzene in contaminated water, under UV and under visible light, for effective implementation in photocatalytic degradation of volatile organic contaminants. Results: The said nanocomposite was crystalline and found to be 40–50 nm in size. No apparent change in the crystal lattice of TiO2 was observed due to the introduction of copper ion, and the nanocomposite also retained a high surface area of 76.28 m2/g. The efficiency of the Cu2O-TiO2 nanoparticles degradation was studied both under UV light and under visible. Cu2O-TiO2 nanoparticles achieved 97 – 99% degradation of benzene, 92 – 97% degradation of toluene and 95 – 98% degradation of chlorobenzene in water. Conclusion: The said Cu2O–TiO2 nanocomposite is photo-active and showed an overall 95% degradation within 2 hours of treatment under the visible region.

Impact of Atmospheric Pressure Fluctuations on Nonequilibrium Transport of Volatile Organic Contaminants in the Vadose Zone: Experimental and Numerical Modeling

AbstractAtmospheric pressure fluctuations can induce subsurface airflow, affecting Volatile Organic Compound (VOC) contaminant migration in the vadose zone. When modeling this process, traditional vapor intrusion models have relied on the assumption of local equilibrium conditions and neglected kinetic mass transfer processes among different phases. In this study, a nonequilibrium multiphase flow and transport model was developed to investigate the impact of atmospheric pressure fluctuations on VOC release from groundwater to the atmosphere. Kinetic mass transfer processes between vapor &amp; liquid phases, and between liquid &amp; solid phases were taken into consideration. A series of soil column experiments with downward/upward pumped gas flow were conducted to validate the model. The experimental results imply the necessity to use nonequilibrium models for quantifying the impact of atmospheric pressure fluctuation. The validated model was used to investigate the role of atmospheric pressure fluctuations for various practical hydrogeologic settings under daily pressure fluctuations. It was found that when the soil organic carbon content is relatively large, the nonequilibrium model more accurately represents VOC migration than a traditional equilibrium model. Therefore, this study suggests the need to apply nonequilibrium vapor intrusion models at sites with high soil organic matter content.

Controlled dehumidification to extract clean water from a multicomponent gaseous mixture of organic contaminants

Rapid expansion of the unconventional oil and gas extraction has increased American energy independence, but also led to increased production of large amounts of contaminated water. Wastewater from the oil and gas industry contains a wide range of contaminants. Injecting such contaminated water into disposal wells or discharging it to the environment jeopardizes freshwater resources. Conventional and membrane-based wastewater treatment techniques are often not effective choices to treat highly contaminated wastewater; however, a suitable way to remove contaminants from wastewater is to selectively separate water in a process analogous to humidification-dehumidification (HDH). Only a few studies have investigated the use of HDH for wastewater treatment. In this study, a novel HDH system is introduced for treating highly contaminated water, such as oil and gas flowback and produced water. In this HDH process, a non-condensable gas, such as air, mixes with wastewater vapor to facilitate the separation of contaminants. As a result, clean water condenses from the multicomponent gaseous mixture while air carries organic contaminants out of the dehumidification section. A laboratory apparatus was constructed and experiments were performed to investigate the HDH process for wastewater treatment and to study the effects of flow dynamics including air flow rate on the composition of treated water. Different contaminants including benzene, toluene, 2-propanol and 2-butoxyethanol were tested. Experimental results showed that the system can be successfully applied for removing volatile and/or toxic organic contaminants from wastewater. A representative multicomponent mixture of fracking wastewater was successfully treated using the experimental setup and clean water with quality of 98.3% was obtained. It was revealed that increasing the air-to-vapor mass ratio improves purity of treated water. Quantitative analysis showed that by increasing the air-to-vapor mass ratio from 0.6 to 5.9, the fraction of separated 2-propanol through the air was improved from 43% to more than 96% of the initial amount. ASPEN software was employed to simulate equilibrium conditions. Experimental results were observed to have lower mass fraction of residual contaminant in the treated water compared to equilibrium state.

Interfacial Solar Distillation for Freshwater Production: Fate of Volatile and Semivolatile Organic Contaminants.

Interfacial solar distillation (ISD) is an approach with low cost and low energy demand useful for seawater desalination and freshwater production. However, the commercial potential of ISD for applications such as polluted seawater desalination or industrial wastewater reuse may be hindered by low rejection of volatile and semivolatile contaminants. For the first time, the results of this study showed that the transport (from bulk water (B) to distilled water (D)) of volatile and semivolatile contaminants during the solar desalination process was highly correlated with compound volatility (R2 = 0.858). The obtained relationship was verified to be capable of predicting the distillation concentration ratio (CD/CB,0) of different contaminants (KH = 6.29 × 10-7-2.94 × 10-4 atm·m3·mol-1) during the ISD process. Compounds such as phenols, which have relatively high volatilization and condensation rates, deserve the most attention as potential contaminants in the distilled water. Meanwhile, other compounds that are more volatile than phenol condensed less in distilled water. Adding an activated carbon adsorbent or a photothermal oxidant is a promising strategy to effectively mitigate the distillation of contaminants and ensure water safety. These results fill the knowledge gap in understanding the transport of volatile and semivolatile compounds in ISD for the treatment of complex source waters.

Volatile organic contaminants (VOCs) emitted from sewer networks during wastewater collection and transport

Presence of volatile organic compounds (VOCs) in sewer networks is a concern due to exposure of workers during maintenance at manholes and repairs of wastewater pipes, and hazard potential for gas explosion. Occurrence, types, and levels VOCs present at the wastewater treatment plant influents in municipalities in Florida (USA) were compared. Gas phase concentrations were estimated by the Henry's law. In addition, gas samples were collected from the sewer lines at one municipality (City of Hallandale Beach, Florida). Comparison of the gas phase concentrations estimated from the liquid influent samples at the wastewater treatment plants with the gas samples collected from the sewer lines showed that gas concentrations estimated by the Henry's law from the influent liquid concentrations underestimate the gas phase VOC levels. The VOCs detected in gas samples collected at the manholes (City of Hallandale Beach) were acetone (11–75.5 μg/m3), chloroform (15–117 μg/m3), chloromethane (1.6–5.6 μg/m3), dichlorodifluoromethane (2.5–4.5 μg/m3), 1,4-dichlorobenzene (2.5–57 μg/m3), ethanol (7.5–329 μg/m3), methylene chloride (0.6–3.2 μg/m3), pentane (4.7–43.9 μg/m3), propane (1.0–2.7 μg/m3), tetrachloroethene (0.88–2410 μg/m3), trichloroethene (0.23–4.4 μg/m3), toluene (5.3–43 μg/m3), and total xylenes (0.48–4 μg/m3).

Exhaustive characterization of (semi-)volatile organic contaminants in car dust using comprehensive two-dimensional gas chromatography ‒ Time-of-flight mass spectrometry

This work represents the first reported effort to build an extensive database of the organic volatile and semi-volatile contaminants present in car dust as a result of migration from materials used in auto-manufacturing. Untargeted analysis of car dust samples has been performed using comprehensive two-dimensional gas chromatography combined with time-of-fight mass spectrometry (GC×GC ‒ToF MS) after generic sample preparation. The enhanced separation power and structural confirmation capabilities provided by this technique have been used for the either positive or tentative identification of 245 GC-amenable compounds, a number of them being identified for the first time in this type of matrix. Information concerning 5 compounds remaining unidentified has also been provided. Results have been summarised in a searchable database containing chromatographic, mass spectral and normalised abundances calculated for the detected analytes in the ten investigated car dusts used to discuss the main findings of the study. Results are expected to serve other researcher to take decisions concerning priority analytes for further evaluation in this research field and for car manufacturers who might search for safer materials.

Screening Analysis of Volatile Organic Contaminants in Industrial Wastewater of GIDC Ankleshwar, Gujarat (India)

Screening Analysis of Volatile Organic Contaminants in Industrial Wastewater of GIDC Ankleshwar, Gujarat (India)