Volatile Chemicals Research Articles

Chemical Composition and Phytotoxic Activity of Artemisia selengensis Turcz. Volatiles.

The chemical profile and allelopathic action of the volatiles produced by Artemisia selengensis were studied. Artemisia selengensis was found to release volatile chemicals to the environment to influence other plants' growth, which suppressed the root length of Amaranthus retroflexus and Poa annua by 50.46 % and 87.83 % under 80 g/1.5 L treatment, respectively. GC/MS analysis led to the identification of 41 compounds (by hydrodistillation, HD) and 48 compounds (by headspace solid-phase microextraction, HS-SPME), with eucalyptol (15.45 % by HD and 28.09 % by HS-SPME) being detected as the most abundant constituent. The essential oil (EO) of A. selengensis completely inhibited the seed germination of A. retroflexus and P. annua at 1 mg/mL and 0.5 mg/mL, respectively. However, eucalyptol displayed much weaker activity compared with the EO, indicating that other less abundant constituents might contribute significantly to the EO's activity. Our study is the first report on the phytotoxicity of A. selengensis EO, suggesting that A. selengensis might release allelopathic volatile agents into the environment that negatively affect other plants' development so as to facilitate its own dominance; the potential value of utilizing A. selengensis EO as an environmentally friendly herbicide is also discussed.

The exposures and health effects of benzene, toluene and naphthalene for Chinese chefs in multiple cooking styles of kitchens.

Commercial cooking has higher intensity and more severe instantaneous cooking pollution from volatile organic chemicals compared to home cooking, making health risk assessment of occupational exposure for chefs a priority. In this study, chefs from three cooking styles of kitchens, including steaming, frying, and grilling, were selected to investigate the external and internal exposures, health risks and effects of several typical aromatic hydrocarbons (benzene, toluene and naphthalene). Naphthalene was found to be the most concentrated contaminant in air samples among the different kitchens, while benzene had the lowest concentration. The concentration of toluene in frying kitchens was significantly higher than that in steaming kitchens. Air concentrations of toluene in frying kitchens, as well as benzene concentrations in grilling kitchens exceeded the standard level according to indoor air quality standard (GB/T18883-2002). Regarding the metabolites of pollutants in urine, the content of S-benzylmercapturic acids (S-BMA) for frying chefs was significantly higher than that for other cooking styles of chefs, which was consistent with the relatively higher air concentrations of toluene. There was a good correlation between internal and external exposure of the pollutants. The level of oxidative stress was influenced by 2-hydroxynaphthalene (2-OHN) and S-BMA, indicating the potential health risks of these occupational exposed chefs. This study indicates the need to improve the monitoring of typical aromatic hydrocarbons, as well as to investigate their potential health effects in large-scale groups, and improve the ventilation in kitchens.

Grass-like plants release general volatile cues attractive for gravid Anopheles gambiae sensu stricto mosquitoes

BackgroundUnderstanding the ecology and behaviour of disease vectors, including the olfactory cues used to orient and select hosts and egg-laying sites, are essential for the development of novel, insecticide-free control tools. Selected graminoid plants have been shown to release volatile chemicals attracting malaria vectors; however, whether the attraction is selective to individual plants or more general across genera and families is still unclear.MethodsTo contribute to the current evidence, we implemented bioassays in two-port airflow olfactometers and in large field cages with four live graminoid plant species commonly found associated with malaria vector breeding sites in western Kenya: Cyperus rotundus and C. exaltatus of the Cyperaceae family, and Panicum repens and Cynodon dactylon of the Poaceae family. Additionally, we tested one Poaceae species, Cenchrus setaceus, not usually associated with water. The volatile compounds released in the headspace of the plants were identified using gas chromatography/mass spectrometry.ResultsAll five plants attracted gravid vectors, with the odds of a mosquito orienting towards the choice-chamber with the plant in an olfactometer being 2–5 times higher than when no plant was present. This attraction was maintained when tested with free-flying mosquitoes over a longer distance in large field cages, though at lower strength, with the odds of attracting a female 1.5–2.5 times higher when live plants were present than when only water was present in the trap. Cyperus rotundus, previously implicated in connection with an oviposition attractant, consistently elicited the strongest response from gravid vectors. Volatiles regularly detected were limonene, β-pinene, β-elemene and β-caryophyllene, among other common plant compounds previously described in association with odour-orientation of gravid and unfed malaria vectors.ConclusionsThe present study confirms that gravid Anopheles gambiae sensu stricto use chemical cues released from graminoid plants to orientate. These cues are released from a variety of graminoid plant species in both the Cyperaceae and Poaceae family. Given the general nature of these cues, it appears unlikely that they are exclusively used for the location of suitable oviposition sites. The utilization of these chemical cues for attract-and-kill trapping strategies must be explored under natural conditions to investigate their efficiency when in competition with complex interacting natural cues.Graphical abstract

Upcycling Poly(Ethylene Terephthalate): Identification of the Recovered Poly(Ethylene Terephthalate) by Thermogravimetry Analysis

The production and utilization of disposal merchandise made of poly(ethylene terephthalate) (PET) continue to increase with an annual rate of ∼2%. The post-consumer PET (PC-PET), accumulated as waste, creates a pseudo-renewable resource which generates opportunities for reusing and recycling. The recycling of PC-PET saves energy and reduces the burden that the waste plastics in landfills and storage facilities impose on the environment. The polymer of this study (PET-R) was purified from PC-PET by a solvent extraction method and was characterized by thermogravimetric analysis (TGA) via five different linear temperature programs. The TGA curves of PET-R showed three distinct regions: the vaporization of the adsorbed volatile organic chemicals (VOCs) at temperatures 60–220 °C, the fast decomposition of the purified PET (PET-R) 350–500 °C, and the slow pyrolysis of the remains at temperatures >500 °C. The values of decomposition energy barrier (Ea), preexponential of the Arrhenius equation (lnA) and the mechanism of decomposition expressed by f(α), for both VOCs and PC-PET, were evaluated by isoconversional methods according to the Kissinger-Akahira-Sunose and Ozawa-Flynn-Wall methods; the results of the two methods were very close to each other for each of the factors in each of the stages. The values of Ea, and lnA of the VOCs decreased with the increase of the extent of the reaction since they were related to the availability of the VOCs. The values of Ea, and A of PET-R were relatively constant with standard deviations of ±4 kJ/mol. The thermal properties of PET-R were close to the properties reported for the pure PET samples. This proves that pure PET can be extracted and purified from PC-PET by solvent extraction for industrial applications and upcycling wastes.

Heptanal inhibits the growth of Aspergillus flavus through disturbance of plasma membrane integrity, mitochondrial function and antioxidant enzyme activity

Fungal contamination poses a threat to agriculture, food production and human health, and a safe and effective method to limit fungal contamination is still needed. In this study, the inhibitory potency of heptanal, a natural volatile chemical, against Aspergillus flavus growth was evaluated, and its mechanism of action was explored. The minimum inhibitory concentrations (MICs) of heptanal vapor fumigation and liquid contact culture were 0.085 and 0.8 μL/mL, respectively. A total of 79 significant differentially abundant metabolites, including 37 upregulated and 42 downregulated ones, were identified in A. flavus mycelia after exposure to 0.8 μL/mL heptanal for 6 h. Metabolomics analysis revealed that heptanal had destructive effects on plasma integrity and mitochondrial function in mycelia. Biochemical analysis confirmed that heptanal caused intracellular substance leakage and resulted in reduced intracellular ATP content, reactive oxygen species (ROS) accumulation, and lower mitochondrial dehydrogenase and ATPase activities. Evaluation of the control efficacy of heptanal fumigation on wheat grain under simulated storage conditions revealed that 225.0 μL/L heptanal vapor could inhibit A. flavus growth under 19% moisture. These results provide insights into the antifungal mechanism of heptanal against A. flavus growth as a promising bio-preservative.

Androstenone induces horses to be more compliant with human–horse interactions

Olfactory signals play an essential role in communication in animals. Pheromones are volatile or nonvolatile chemicals that trigger social responses among animals. Therefore, pheromone treatment could, in theory, be used to modify horse behavior to improve human–horse relationships. Androstenone (5α-androst-16-en-3-one) is a steroidal pheromone found in the saliva of boars and elicits responses across species. However, its role in horse behaviors is not elucidated. This study investigated the effect of androstenone on horse behavior. Trainability (lowering head and moving hindfeet) and calmness tests (standing still with or without a stimulator) were performed with or without applying androstenone diluted with jojoba oil. Treatment with 10 μg/mL of androstenone applied 30 minute before the tests significantly decreased the time for the horses to lower their head compared with the control. The results of the calmness tests had no significant differences compared with the control group. In the pressure mediation test for trainability assessment, a group of horses treated with 10 μg/mL of androstenone moved their hind feet in a significantly shorter time (P < 0.05) than the control group. As a result, androstenone appears to induce horses to be more accepting of general management and training.

Development of a Model for Predicting the Volatilization Flux from Unsaturated Soil Contaminated by Volatile Chemical Substances

This work developed a model for predicting the volatilization flux from the unsaturated soil contaminated by volatile chemical substances (VCSs) such as mercury and benzene. The model considers a series of phenomena under the unsaturated condition such as multi-phase flow consisting of a non-aqueous phase liquid, water, and gases together with the permeation of rainfall into the surface soil, the volatilization/condensation of VCSs, and the adsorption/desorption of VCSs. On this basis, this work clarified a mechanism for the generation of a volatilization flux at the ground surface. In addition, the effects of various transport phenomena in the surface soil on the magnitude and seasonal changes in this flux due to variations in weather factors such as rainfall level, temperature, and air pressure were quantitatively evaluated. This newly developed prediction model can be utilized to estimate dynamic variations in the flux under real-environmental conditions.

Host plant shift differentially alters olfactory sensitivity in female and male Drosophila mojavensis

Animals may vary in their utilization of plants depending on plant availability, and also on the sex of the animal. Evolutionary adaptations may arise, particularly in specialist animals to the chemistry of the host plants, and these adaptations may differ between the sexes due to differences in their interactions with the plants. Drosophila mojavensis uses different host cacti across its range, and volatile chemicals emitted by the host are the primary cue for host plant identification. In this study, we measured responses of individual olfactory sensory neurons to a large suite of odorants across males and females of the two southern D. mojavensis populations. We show that a switch in host plant is accompanied by changes in the olfactory system, but the effect of this switch is minor compared to that of sex. That is, we observe differences in olfactory receptor neuron specificity and sensitivity to odorants between sexes, and to a lesser extent between populations. The majority of sensory differences are restricted to only three of the 17 sensory neurons measured. Further, we found numerous differences between sexes that only occur within one population, i.e., sex-by-population interactions.

Electrochemical Recycling of Photovoltaic Modules to Recover Metals and Silicon Wafers

AbstractAn electrochemical‐assisted leaching process using boron‐doped diamond (BDD) electrodes was developed to recover valuable metals from photovoltaic modules. With BDD electrodes peroxydisulfate is generated from sulfuric acid to oxidatively dissolve copper, tin and silver from solar cell contacts. Since the oxidant is regenerated in the developed process, no additional hazardous and volatile chemicals are required, and the process can be operated solely by electricity. In addition, the dissolved metals can be electrochemically recovered at the cathode of the same cell.

Sensitive and robust chemical detection using an olfactory brain-computer interface

When it comes to detecting volatile chemicals, biological olfactory systems far outperform all artificial chemical detection devices in their versatility, speed, and specificity. Consequently, the use of trained animals for chemical detection in security, defense, healthcare, agriculture, and other applications has grown astronomically. However, the use of animals in this capacity requires extensive training and behavior-based communication. Here we propose an alternative strategy, a bio-electronic nose, that capitalizes on the superior capability of the mammalian olfactory system, but bypasses behavioral output by reading olfactory information directly from the brain. We engineered a brain-computer interface that captures neuronal signals from an early stage of olfactory processing in awake mice combined with machine learning techniques to form a sensitive and selective chemical detector. We chronically implanted a grid electrode array on the surface of the mouse olfactory bulb and systematically recorded responses to a large battery of odorants and odorant mixtures across a wide range of concentrations. The bio-electronic nose has a comparable sensitivity to the trained animal and can detect odors on a variable background. We also introduce a novel genetic engineering approach that modifies the relative abundance of particular olfactory receptors in order to improve the sensitivity of our bio-electronic nose for specific chemical targets. Our recordings were stable over months, providing evidence for robust and stable decoding over time. The system also works in freely moving animals, allowing chemical detection to occur in real-world environments. Our bio-electronic nose outperforms current methods in terms of its stability, specificity, and versatility, setting a new standard for chemical detection.

Juvenile Experience with Male Cues Triggers Cryptic Choice Mechanisms in Adult Female Redback Spiders.

Simple SummaryFemales of many species vary in their receptivity to male mating attempts. When many males are present in the habitat, the theory predicts that females should be choosy and discriminate among potential mates. When few males are available, females should mate readily with the first male who courts, and thus avoid the risk of remaining unmated. We predicted that cues perceived as juveniles that indicate male availability would affect the mating behaviour of adult females. In our first experiment, juvenile females were exposed to airborne chemicals produced by males at high or low densities. In our second experiment, we mimicked a natural situation where males or other juveniles live on the webs of females shortly before they become sexually mature, and compared this to females developing in isolation. As was consistent with our predictions, we found that the adult females changed their behaviour after exposure to cues of high male availability during development. When the females perceived many males nearby (high density airborne cues or living with males) they more often interrupted copulation, or cannibalized the males before the mating was complete as adults. In comparison, when the cues indicated low male availability, the adult females were more likely to allow the males to complete mating, and cannibalism was less common.Female choice may be linked to population density if the expected encounter rates with potential mates affects choosiness (the energy and risk engaged to express mate preferences). Choosiness should covary with male availability, which could be assessed using the social cues available during development. We tested whether the exposure of juvenile females to cues of male density affected the mechanisms of choosiness of adult Latrodectus hasselti spiders in two experiments simulating natural contexts. The juvenile females were exposed to (1) volatile chemicals from two densities of adult males (airborne cues), and (2) tactile, vibrational and chemical cues from adult males or other females (cohabitation cues). As adults, the females mated readily, regardless of the treatment, but there was strong evidence for post-copulatory mechanisms of choosiness in females exposed to cues of high male availability. These included abbreviated matings (in both experiments), cannibalism of the males before the mating was complete (cohabitation), and, remarkably, a reduction in the successful placement of internal sperm plugs (cohabitation). These shifts decrease the likelihood that the first mate would monopolize paternity if the female chose to mate again. We conclude that female choosiness may impose a strong selection on males despite the high mating rates, and these effects can hinge on the cues of male availability detected by juveniles.

Liver Impairment-The Potential Application of Volatile Organic Compounds in Hepatology.

Liver diseases are currently diagnosed through liver biopsy. Its invasiveness, costs, and relatively low diagnostic accuracy require new techniques to be sought. Analysis of volatile organic compounds (VOCs) in human bio-matrices has received a lot of attention. It is known that a musty odour characterises liver impairment, resulting in the elucidation of volatile chemicals in the breath and other body fluids such as urine and stool, which may serve as biomarkers of a disease. Aims: This study aims to review all the studies found in the literature regarding VOCs in liver diseases, and to summarise all the identified compounds that could be used as diagnostic or prognostic biomarkers. The literature search was conducted on ScienceDirect and PubMed, and each eligible publication was qualitatively assessed by two independent evaluators using the SANRA critical appraisal tool. Results: In the search, 58 publications were found, and 28 were kept for inclusion: 23 were about VOCs in the breath, one in the bile, three in urine, and one in faeces. Each publication was graded from zero to ten. A graphical summary of the metabolic pathways showcasing the known liver disease-related VOCs and suggestions on how VOC analysis on liver impairment could be applied in clinical practice are given.

Ethanol-based disinfectant sprays drive rapid changes in the chemical composition of indoor air in residential buildings

The COVID-19 pandemic has resulted in increased usage of ethanol-based disinfectants for surface inactivation of SARS-CoV-2 in buildings. Emissions of volatile organic compounds (VOCs) and particles from ethanol-based disinfectant sprays were characterized in real-time (1 Hz) via a proton transfer reaction time-of-flight mass spectrometer (PTR-TOF-MS) and a high-resolution electrical low-pressure impactor (HR-ELPI+), respectively. Ethanol-based disinfectants drove sudden changes in the chemical composition of indoor air. VOC and particle concentrations increased immediately after application of the disinfectants, remained elevated during surface contact time, and gradually decreased after wiping. The disinfectants produced a broad spectrum of VOCs with mixing ratios spanning the sub-ppb to ppm range. Ethanol was the dominant VOC emitted by mass, with concentrations exceeding 103 μg m−3 and emission factors ranging from 101 to 102 mg g−1. Listed and unlisted diols, monoterpenes, and monoterpenoids were also abundant. The pressurized sprays released significant quantities (104–105 cm−3) of nano-sized particles smaller than 100 nm, resulting in large deposited doses in the tracheobronchial and pulmonary regions of the respiratory system. Inhalation exposure to VOCs varied with time during the building disinfection events. Much of the VOC inhalation intake (>60 %) occurred after the disinfectant was sprayed and wiped off the surface. Routine building disinfection with ethanol-based sprays during the COVID-19 pandemic may present a human health risk given the elevated production of volatile chemicals and nano-sized particles.

Identification of Priority Air Pollutants in Confined Spaces

Introduction: Owing to the rapid development of digital technologies, most people nowadays are working indoors while using no machinery or equipment and being unexposed to volatile industrial chemicals. Yet, people staying inside for too long often complain of poor indoor air quality and microclimate. Our objective was to study air pollutants in a simulation experiment with continuous human occupancy inside unventilated confined spaces. Materials and methods: Up-to-date sensitive analytical techniques, such as photoionization, laser nephelometry, gas-phase chemiluminescence, spectrophotometry, high-performance liquid chromatography with diode array detection (HPLCDAD) and gas chromatography–mass spectrometry (GC-MS), were used to determine indoor air pollutants. Results: We compared changes in airborne concentrations of nitrogen oxides, prop-2-enenitrile, acetaldehyde, benzene, but-2-enal, airborne particulate matter (PM2,5 and PM10), methylbenzene, 2-methylbuta-1,3-diene, formaldehyde, prop-2-en-1-al, carbon oxide and dioxide following 1.5, 3.0, and 4.5 hours of stay of volunteers in a 15.9 m2 room (4.0 m2 per person; a 2.55 m ceiling height) against background levels. The established human occupancy-related priority pollutants included acetaldehyde, formaldehyde, prop-2-en-1-al, and carbon dioxide. Laboratory testing showed the presence of 83 volatile and semivolatile organic chemicals in the unventilated room, among which aromatic hydrocarbons, esters and aldehydes prevailed. Conclusion: Our findings could be useful for designing ventilation systems in confined spaces and optimizing the workbreak schedule during the working hours.

Impact of heat on biological concentrations of toluene and acetone resulting from exposure by inhalation: A pilot study

Climatic conditions raise new concerns about the potential impact of heat on the absorption and kinetics of certain chemicals. The impact of 3 temperatures (21, 25 and 30 °C WBGT) on the toxicokinetics of toluene and acetone was therefore evaluated in five human subjects during controlled exposures in an inhalation chamber. Biological samples were collected and analyzed by GC–MS/MS. Increases between 4 and 85 % were observed for solvents concentrations in blood (30 vs 21 °C) while decreases in urine samples for acetone and o-cresol were measured at the end of the exposure period (4 h). Mean blood concentrations at 4 h are well correlated with temperature. Results suggest an increased absorption and/or a decreased elimination of volatile chemicals in the presence of heat. Higher increases of blood chemical concentrations were observed in heavier individuals. Further studies should include physiologically based toxicokinetic models to help in better understanding the mechanisms involved and their respective contribution.

Can We Get the Full Picture? Comparison of a Series of Volatile Chemicals’ Action on Gene Expression in A549 Cells as Part of a Read-Across Approach

Can We Get the Full Picture? Comparison of a Series of Volatile Chemicals’ Action on Gene Expression in A549 Cells as Part of a Read-Across Approach

Adsorbing Volatile Organic Chemicals by Soluble Triazine-Based Dendrimers under Ambient Conditions with the Adsorption Capacity of Pyridine up to 946.2 mg/g.

Two triazine-based dendrimers with peripheral 1,3,5-triamidobenzene (1-3-5-TAB) functionality were prepared, and their void spaces in the bulk solid were investigated. We examined dendrimers of three core lengths and determined the one with the longest core exhibits the largest void space because the peripheral amides were not imbedded in the internal space of each dendritic molecule. The new dendrimers as solids were observed to adsorb volatile organic chemicals efficiently. Importantly, because the dendrimers are soluble in organic solvents, the adsorbed VOCs can be quantified by 1H-NMR spectroscopy by choosing a chemical shift (δ) of dendrimers as the internal standard to exclude interfering impurity signals, a much simpler and more efficient protocol than the traditional GC technique for the VOC quantification. One dendrimer was found to adsorb 24 equivalents of pyridine, so its adsorption capacity is equivalent to 946.2 mg/g. This is a more than 2-fold increase than the reported values by other porous materials.

Determination of volatile substances in olives and their effect on reproduction of the olive fruit fly

AbstractFemales of the olive fruit fly Bactrocera oleae lay their eggs in olives mainly using fruit volatile stimuli. Using GC‐MS analysis, we determined the chemical composition of the volatile blend emitted from field‐collected olive fruit of cv. Megaritiki, at different stages of maturity. GC‐MS analysis demonstrated qualitative and quantitative differences in the headspace blend emitted by the olive fruit. Certain chemicals such as toluene, n‐octane, α‐pinene, limonene, ethyl hexanol, nonanal n‐dodecane, decanal and n‐tetradecane were detected in greater amounts, irrespective of the growth stage of the fruit. The flies’ exposure to a number of these chemicals, such as n‐octane and α‐pinene, as well as to a mixture consisting of n‐octane, α‐pinene, limonene, ethyl hexanol, nonanal, n‐dodecane, decanal and n–tetradecane favoured successful mating and egg production. The results may contribute to the improvement of the mass rearing of the fly, through these findings, which illustrate the positive effect that certain fruit volatile chemicals have on the fly's reproduction and offer a better understanding of the relation between the fly and the host fruit.

Drastically boosting volatile acetone capture enabled by N-doping activated carbon: An interesting deep surface digging effect

Affording the ultrahigh structural properties and rich surface groups in traditional activated carbon (AC) together to enable the efficient control of polar volatile organic chemicals (VOCs) is significant but challenged. Herein, we report the skilled construction of super activated carbon (AC) adsorbent (SBET = 4402 m2 g−1) via N-doping tactic to trigger the deep surface digging effect for banana peel-derived AC (SBET = 3897 m2 g−1) and remarkably reinforced the multilayer adsorption behavior by the post-implanted surface N species. Impressively, the resultant optimized adsorbent UC-5 shows nearly 1.83 folds enhancement of polar VOCs(volatile organic chemicals) that acetone adsorption capacity (44.89 mmol g−1) under 30 kPa of acetone partial pressure compared to the original AC (24.57 mmol g−1), which is known as the record acetone adsorption capacity. Besides, the boosting adsorption effect was well inherited and enlarged under a higher saturated vapor pressure of acetone in the static adsorption process, which was further evidenced by dynamic adsorption breakthrough experiments. The intensive studies revealed that the surface digging of the used urea dopant not only contributed to the enriching of surface N and improved the structural properties and thermal stability (575 °C) but also reserved more oxygen content of original AC compared to the resulted counterparts using melamine, which were together responsible for the drastic increase of acetone adsorption. This work provides the new possibility for the adsorption of polar VOCs gas via exploiting the outstanding structural properties and surface N interaction.

Non-Thermal Milk and Milk Products Processing

Manufacture of virtually all milk and dairy products involves heat treatment, with the goal of killing bacteria and inactivating enzymes, among other things. Thermal reactions, on the other hand, might result in undesired changes such as protein denaturation, non-enzymatic browning, the creation of a cooked flavour, nutritional quality loss (vitamins and volatile chemicals), bacterial inhibitor inactivation, and rennet ability deterioration. Over and above the thermal processes are characterized as the most energy-consuming technologies in the food industry. As a result, a number of contemporary developments and non-thermal technologies have been investigated and found to have no negative impact on milk quality; for example, High hydrostatic pressure (HHP), Ionization Radiation, Ultrasounds (US), Pulsed electric fields (PEF), carbon dioxide, High Voltage Arc Discharge (HVAD) , Cold Plasma (CP), Bio-control cultures, Non-conventional chemical reagents, Ozonation, and Protective and preserving packaging technologies for processing milk have devised to replace heat treatment. The focus of this review is on certain non-thermal processing innovation as an emerging technology and its application on dairy products.