Evaluation of potential sample contamination from a self-designed automatic device for volatile organic compounds (VOCs) active air sampling.

Rationale for Soil‐Gas Sampling to Improve Vapor Intrusion Risk Assessment in China

First posted June 5, 2023 For additional information, contact: Director, New Jersey Water Science CenterU.S. Geological Survey3450 Princeton Pike, Suite 110Lawrenceville, NJ, 08648Contact Pubs Warehouse Groundwater wells and surface-water storm sewers contaminated with volatile organic compounds (VOCs) and per- and polyfluoroalkyl substances (PFASs) at the former Naval Air Warfare Center (NAWC) site in West Trenton, New Jersey were sampled in 2018 as part of the Navy’s long-term monitoring program. Trichloroethene (TCE), cis-1,2-dichloroethene (cisDCE), and vinyl chloride concentrations were plotted in map view and selected cross sections to elucidate the vertical and horizontal extent and distribution of contamination, along with a tabular comparison between 2018 and previous analytical results. The 2018 data showed that the areas of VOC contamination (>1 microgram per liter) decreased slightly on the north and east sides of the NAWC site from previous sampling dates; these decreases are attributed to the influence of the pump-and-treat system, natural attenuation processes, and various engineered bioaugmentation experiments that have occurred onsite. Off-site groundwater samples indicate the VOC contaminated groundwater is likely hydraulically constrained by the pump-and-treat system and appears to not be moving offsite to the south and west of NAWC. Only one offsite well, 50BR, located along the eastern margin of the site, was found to have detectable TCE and cisDCE concentrations, indicating that VOC contamination continues to migrate a short distance offsite to the east. Detectable VOC contamination was found in wells as deep as 200 and 221 feet on both the east and west sides of the NAWC site. Comparisons of present-day data to data from past sampling efforts indicate that TCE concentrations in most wells have decreased slowly over time.Results from surface-water samples indicate that VOCs enter surface water predominantly through the West Ditch drainage system. Concentrations and fluxes of VOCs are higher when groundwater levels are higher, indicating contaminated groundwater discharges into the surface water system. Higher VOC concentrations at the Interceptor site relative to other sites in the West Ditch indicate the contamination in the West Ditch system is likely caused by contaminated groundwater discharging to the West Ditch storm sewer near manhole MH-140 when water table levels are high.The pump-and-treat extraction wells at the former NAWC site were sampled for per- and polyfluoroalkyl substances (PFAS) in 2018. The suite of reported PFAS include perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), perfluorononanoic acid, and perfluorobutane sulfonate. Concentrations were plotted in map view to determine the areal extent of the PFAS contamination at the site. Extraction well 48BR sampled on the eastern half of the site was found to have PFOS and PFOA concentrations greater than the New Jersey Department of Environmental Protection Drinking Water maximum contaminant levels (MCLs), which is consistent with the distribution of highest PFAS concentrations in surface water in the OF-4 storm sewer system that drains that area, as well as previously collected PFAS concentrations in monitoring wells. On the western half of the site, the extraction well 08BR sample exceeded MCLs for PFOA and PFOS and the extraction well 22BR sample exceeded the MCL for PFOA, but samples from all other extraction wells were below the MCLs or other criteria for all PFAS analyzed. Concentrations of PFOA exceeded concentrations of PFOS on the west side of NAWC in both groundwater and surface water, which contrasts with the conditions on the east side of NAWC where PFOS concentrations exceeded PFOA concentrations. However, this observation was based on a limited number of samples on the west side of NAWC from 2018 and previous years, so more PFAS sampling is needed on the west side to assess this further.

Cancer diagnosis by breath analysis: what is the future?

Volatile organic compounds (VOCs) play a crucial role in emission control, being one of the most important sources of odor while also serving as significant precursors to secondary organic aerosols and ozone formation. Appropriate sampling methods are essential for accurately assessing the concentration and composition of VOCs within swine barns. In this study, the effects of both passive air sampling and active air sampling on VOCs were evaluated, and the influence of storage time on the VOC stability in sampling canisters for both methods was investigated. SUMMA canisters, which are electropolished and passivated with silanization, offer excellent corrosion protection and resistance to high pressure and temperature and were used in this study. The predominant component categories prevailing within the pig house were found to be oxygenated VOCs (OVOCs) and volatile sulfur compounds (VSCs), with ethanol emerging as the most abundant component of VOCs detected. Notably, the statistical analysis results revealed no significant differences between passive and active sampling regarding the impact of storage time on substance concentration. Changes in canister pressure also did not significantly affect substance stability. The results showed that the C2–C3 compounds remained relatively stable, especially within 3 days, with recoveries above 80% within 20 days. Methyl sulfide, dimethyl disulfide, and ethanol were more stable within the first week, but their recoveries significantly dropped by day 20, with methyl sulfide and dimethyl disulfide at 62.3% and 65.3%, respectively. This study contributes to the development of a foundation for selecting appropriate VOC sampling methods in swine facilities for conducting a rational analysis of VOC samples.

When determining whether or not remediation of subslab contamination is warranted, it is often important to know if the presence of volatile organic compounds (VOCs) in indoor air is caused primarily by interior sources, or primarily by subslab contamination. With a Building Pressure Control test, the pressure differential across the building envelope and, thereby, also the pressure differential across the slab, can be controlled by a blower. By measuring the indoor air concentrations of VOCs under depressurization (upward pressure gradient over the slab) and under pressurization (downward pressure gradient over the slab), it can be determined if the subslab contamination contributes significantly to the VOC concentrations in indoor air. This technique has been applied at several sites in the Central Denmark Region, and the results show that a Building Pressure Control test is a quick and effective method to examine if VOC contamination in indoor air is caused primarily by interior sources or primarily by subslab sources. With numerous measurement points in the indoor air, at some sites this test method has identified the area where the subslab contamination is located. A pressure differential at ‒5/+5 Pa across the building envelope was sufficient at all the test sites to control the pressure gradient across the slab to be uniquely upward/downward.

Background: Emissions from cooking fuels that include many health damaging pollutants such as fine particulate matter and a range of polycyclic aromatic hydrocarbons and volatile organic compounds (VOCs) are a major public health concern in low and middle income countries (LMICs). Despite the ubiquity of exposures in India, VOC profiles in rural and urban households are poorly understood. Methods: We report results from cooking period measurements conducted in 112 (56 biomass, 23 kerosene and 34 gas using ) rural and urban households that were part of the larger Tamil Nadu Air Pollution and Health Effects (TAPHE) cohort study in Southern India. Samples were collected on a mixed-bed sorbent (Tenax and Carbopack) tubes. Active air sampling was performed using pre-calibrated constant flow pumps (SKC Inc., PA, USA) set to a flow rate of 0.1 L/min for 100 min. An automated thermal desorption unit connected to GC-MS system was used to quantify 59 VOCs. Pentafluorobenzene, 1,4-difluorobenzene and chlorobenzene-d5 were used as internal standards and percent recovery ranged from 81.7% to 119.9%.Results: Total VOC (TVOC) concentrations in rural homes (4426.8 µg/m3) were significantly higher when compared to urban homes (2010.9 µg/m3). Toluene, styrene, m,p-xylene and benzene were dominant in rural kitchens whereas toluene, m,p-xylene, benzene and isopropyltoluene were dominant in urban kitchens during cooking. Mean TVOC concentrations were the highest in biomass using homes (4617 µg/m3) followed by LPG (2839.7 µg/m3) and kerosene (1639.8 µg/m3) respectively. Benzene levels consistently exceeded the National Ambient Air Quality Guideline value of 5µg/m3 in all rural and urban homes. Winter season, open field burning and industry nearby were associated with significantly higher VOC concentrations.Conclusions: Additional large scale assessments of population exposure to VOCs are needed in LMICs to better characterize health risks associated with solid fuel use.

BackgroundMicroorganisms synthesize and release a large diversity of small molecules like volatile compounds, which allow them to relate and interact with their environment. Volatile organic compounds (VOCs) are carbon-based compounds with low molecular weight and generally, high vapor pressure; because of their nature, they spread easily in the environment. Little is known about the role of VOCs in the interaction processes, and less is known about VOCs produced by Malassezia, a genus of yeasts that belongs to the human skin mycobiota. These yeasts have been associated with several dermatological diseases and currently, they are considered as emerging opportunistic yeasts. Research about secondary metabolites of these yeasts is limited. The pathogenic role and the molecular mechanisms involved in the infection processes of this genus are yet to be clarified. VOCs produced by Malassezia yeasts could play an important function in their metabolism; in addition, they might be involved in either beneficial or pathogenic host-interaction processes. Since these yeasts present differences in their nutritional requirements, like lipids to grow, it is possible that these variations of growth requirements also define differences in the volatile organic compounds produced in Malassezia species.Aim of reviewWe present a mini review about VOCs produced by microorganisms and Malassezia species, and hypothesize about their role in its metabolism, which would reveal clues about host-pathogen interaction.Key scientific concepts of reviewSince living organisms inhabit a similar environment, the interaction processes occur naturally; as a result, a signal and a response from participants of these processes become important in understanding several biological behaviors. The efforts to elucidate how living organisms interact has been studied from several perspectives. An important issue is that VOCs released by the microbiota plays a key role in the setup of relationships between living micro and macro organisms. The challenge is to determine what is the role of these VOCs produced by human microbiota in commensal/pathogenic scenarios, and how these allow understanding the species metabolism. Malassezia is part of the human mycobiota, and it is implicated in commensal and pathogenic processes. It is possible that their VOCs are involved in these behavioral changes, but the knowledge about this remains overlocked. For this reason, VOCs produced by microorganisms and Malassezia spp. and their role in several biological processes are the main topic in this review.

Uncertainties in monitoring of SVOCs in air caused by within-sampler degradation during active and passive air sampling

A new cell for single sided headspace sampling has been developed for the analysis of volatile organic compounds from food packaging paperboard and laminated paperboard. The cell, which samples the volatile organic compounds over a selected surface, is useful for determining the barrier function of laminated paperboards with respect to volatile compounds. The analysis of volatile organic compounds is carried out by purge and trap capillary gas chromatography in combination with mass spectrometric detection and compound identification. The new sampling cell was constructed to facilitate specific analysis of organic compounds from only one side of a laminated paperboard. The construction and the operating principles of the new sampling device are described. The repeatability of the single sided headspace procedure was found to be quite good. Relative standard deviations of about 5–7% were obtained for the major compounds quantified in replicate headspace analyses of a laminated paperboard. The volatile compounds released from the inner side of a food packaging paperboard sample with different surface composition on the two sides were determined. The barrier function against volatile organic compounds of some laminated paperboards was investigated employing the new headspace cell.

Soil microbes produce an immense diversity of metabolites, including volatile organic compounds (VOCs), which can shape the structure and function of microbial communities. VOCs mediate a multitude of microbe-microbe interactions, including antagonism. Despite their importance, the diversity and functional relevance of most microbial volatiles remain uncharacterized. We assembled a taxonomically diverse collection of 48 Actinobacteria isolated from soil and airborne dust and surveyed the VOCs produced by these strains on two different medium types in vitro using gas chromatography-mass spectrometry (GC-MS). We detected 126 distinct VOCs and structurally identified approximately 20% of these compounds, which were predominately C1 to C5 hetero-VOCs, including (oxygenated) alcohols, ketones, esters, and nitrogen- and sulfur-containing compounds. Each strain produced a unique VOC profile. While the most common VOCs were likely by-products of primary metabolism, most of the VOCs were strain specific. We observed a strong taxonomic and phylogenetic signal for VOC profiles, suggesting their role in finer-scale patterns of ecological diversity. Finally, we investigated the functional potential of these VOCs by assessing their effects on growth rates of both pathogenic and nonpathogenic pseudomonad strains. We identified sets of VOCs that correlated with growth inhibition and stimulation, information that may facilitate the development of microbial VOC-based pathogen control strategies. IMPORTANCE Soil microbes produce a diverse array of natural products, including volatile organic compounds (VOCs). Volatile compounds are important molecules in soil habitats, where they mediate interactions between bacteria, fungi, insects, plants, and animals. We measured the VOCs produced by a broad diversity of soil- and dust-dwelling Actinobacteria in vitro. We detected a total of 126 unique volatile compounds, and each strain produced a unique combination of VOCs. While some of the compounds were produced by many strains, most were strain specific. Importantly, VOC profiles were more similar between closely related strains, indicating that evolutionary and ecological processes generate predictable patterns of VOC production. Finally, we observed that actinobacterial VOCs had both stimulatory and inhibitory effects on the growth of bacteria that represent a plant-beneficial symbiont and a plant-pathogenic strain, information that may lead to the development of novel strategies for plant disease prevention.

ABSTRACTThis study investigates the volatile organic compounds (VOCs) constituents and concentration levels on a new university campus, where all of the buildings including classrooms and student dormitories were newly built and decorated within 1 year. Investigated indoor environments include dormitories, classrooms, and the library. About 30 dormitory buildings with different furniture loading ratios were measured. The characteristics of the indoor VOCs species are analyzed and possible sources are identified. The VOCs were analyzed with gas chromatography–mass spectroscopy (GC-MS). It was found that the average total VOC (TVOC) concentration can reach 2.44 mg/m3. Alkenes were the most abundant VOCs in dormitory rooms, contributing up to 86.5% of the total VOCs concentration. The concentration of α-pinene is the highest among the alkenes. Unlike the dormitory rooms, there is almost no room with TVOC concentration above 0.6 mg/m3 in classroom and library buildings. Formaldehyde concentration in the dormitory rooms increased about 23.7% after the installation of furniture, and the highest level reached 0.068 mg/m3. Ammonia released from the building antifreeze material results in an average indoor concentration of 0.28 mg/m3, which is 100% over the threshold and should be seriously considered. Further experiments were conducted to analyze the source of the α-pinene and some alkanes in dormitory rooms. The results showed that the α-pinene mainly comes from the bed boards, while the wardrobes are the main sources of alkanes. The contribution of the pinewood bed boards to the α-pinene and TVOC concentration can reach up to above 90%. The same type rooms were sampled 1 year later and the decay rate of α-pinene is quite high, close to 100%, so that it almost cannot be detected in the sampled rooms.Implications: Analysis of indoor volatile organic compounds (VOCs) in newly built campus buildings in China identified the specific constituents of indoor VOCs contaminants exposed to Chinese college students. The main detected substances α-pinene, β-pinene, and 3-carene originated from solid wood bed boards and should be seriously considered. In addition, the contribution rates of building structure materials and furniture to specific VOCs constituents are quantitative calculated. Also, the decay rates of these specific constituents within 1 year are also quantitative calculated in this paper. This study can help us to better understand the sources and concentration levels of VOC contaminants in campus buildings, and to help select appropriate materials in buildings.

Background: In recent research, optical sensors gained a growing interest motivated by the increasing need for specific sensors that allow for routine and effective measurements in several fields and analysis such as, safety, environment, and human health. Among optical sensors are photonic crystal sensors, which are characterized by high sensitivity and biocompatibility. The variations inside and around the photonic crystal can give important information by measuring the wavelength, the band gap, the output power…etc. Through defects created in photonic crystals such as missing rows of holes or rods, light is guided through and the goal is to achieve a very high sensitivity and spatial selectivity to changing superior bulk devices. In this study, we model a new structure of an optical channel drop filter (CDF) based on 2-dimensional photonic crystals to detect volatile organic compounds that can infect human health. Objective: Detect the variation of the refractive index by fixing the radius (r) at 99.37nm and the lattice constant (a) at 523nm for various volatile organic compounds such as H2CO, CH2Cl2, and C2Cl4 with refractive indexes that are: 1.3746, 1.421 and 1.503 respectively in the optical sensor based on photonic crystals for reasons related to the protection of human health. Methods: The structure is made of square lattice silicon rods immersed in air. The dielectric constant of silicon and air is 11.9716 and 1 respectively. First, we created a cross shape resonator and designed an optical channel drop filter in the heart of the structure; our method is based on plane wave expansion method (PWE) by using MATLAB software and the finite element method (F.E.M) with COMSOL software. Results: Three volatile compounds have been studied, such as Dichloromethane used as synthesis intermediate by the chemical industry or solvent used in the pharmaceutical or medical industry. Acute inhalation exposure may cause severe optic neuropathy and liver attack (Hepatitis). Then, the Methanal is used to dry or kill the skin taking as an example, the medical treatment of warts. And perchlorethylene is used for the dry cleaning of tissues and for degreasing metals because it is in category 3 carcinogens, toxic to the nervous system and the kidney. These three volatile compounds where introduced and studied in the proposed structure. The results obtained through this study are as follows: diagram of the TM and TE bands of the photonic crystal in a square array of silicon rods embedded in the air, schematic diagram of the filter, distribution of the refractive index along the structure, structure meshing, propagation and transmission for different refractive indices such as methanal (H2CO), dichloromethane (CH2Cl2) and perchlorethylene (C2Cl4). Conclusion: In this article, we have been able to simulate, analyze and control our proposed structure with MATLAB and COMSOL software based on the finite element method. The results show that for the three volatile organic compounds, the variation of the signal is due to the wavelength of the resonance which is related to the refractive index (n). This can be seen by the small Δλ between three volatile organic compounds, which is 0.4nm between (H2CO, C2Cl4) and 2.9 nm between (CH2Cl2, H2CO). Thanks to this change, this structure can be used as sensor for the detection of toxic organic pollutants that can infect human health (16).

Volatile organic compounds (VOCs) are an important source of contamination of groundwater supplies in Massachusetts and many parts of the United States. One local response is to require sewering in wellhead protection areas as an easily enforceable policy designed to reduce the probability of VOC contamination of groundwater. Data were collected for 238 wellhead protection areas in Massachusetts on VOC contamination levels and the sewered and unsewered land uses in those aquifer recharge areas. Logistic regression procedures were used to see whether sewering had any statistical effect on likelihood of contamination of well water. The results provided limited, but not overpowering, support for the idea that requiring commercial and industrial land uses to use sewers would reduce the chance of VOC contamination.

EMF response of the YSZ based potentiometric sensors in VOC contaminated air

Prunella vulgaris (PV) is a low-growing perennial herb, which can be found in different parts of the world as Asia, Europe and North America. It is traditionally used for medicinal treatment in various cultures in India, China, Japan, Korea, Russia, and Eastern Europe for treating different ailments, such as fever, and healing wounds. In our previous article, we showed the anti-tumorous effect of the volatile organic compounds (VOCs) of PV and characterized the steam distillation process in the extraction of VOCs from PV. This has never been done before as we are aware of. To use the VOCs as drugs, there is a question of how much of the VOCs are lost before the prepared drugs reach the patients. Thus, the first aim of the present article is to try to explore the time depletion effect on the VOCs in the PV extracts. Then, the second aim is to extend the work in the previous paper and further understand the dynamics of the distillation process of PV by changing the steam flow rate in the extraction process. To achieve the first aim to explore the aging effect of how much VOCs are depleted after they are extracted, the VOCs were first extracted by the same method as before, i.e., using steam distillation. Then, tubes of the aqueous solution containing the VOCs were then stored in a 5°C refrigerator. They were then taken out for GC-MS analysis according to a preplanned schedule up to 8 weeks after the VOCs were extracted. The chemical composition of the distillate could then be evaluated. This revealed the changes in the abundance of VOCs with aging. At the same time, the cell viability of SCC154 oral squamous cells treated by these herbal solutions, which were at different aging stages, was evaluated using a tetrazolium-based colorimetric reagent, Cell Counting Kit-8. To achieve the second aim of exploring the dynamics of the steam distillation process, the steam flow rate was adjusted by changing the temperature setting of the hot plate. GC-MS was again used to quantify the chemical constituents of the distillates. By using GC-MS to measure the abundance of volatile compounds at different time points after the distillation process, it was found that the volatile compounds persist for a very long time, or over 8 weeks, which was the longest period of our experiment. The aging of the distillates also did not depreciate much the cell cytotoxicity of the PV distillate on the cancer cells. With respect to the dynamics of the steam distillation process, it was found that, at a low steam flow rate, volatile compounds of lower molecular weight are more efficient to be extracted, while at a high steam flow rate, volatile compounds of higher molecular weight are more efficiently extracted. Our findings demonstrate that the VOC compounds extracted and present in aqueous form do not deplete much for at least 2 months after the extraction process, neither they exhibit cell cytotoxicity. The experiments on the dynamics of the steam distillation process demonstrate that the mass of herb present in the flow path of the steam has significant effects on the relative amounts of VOCs extracted.