Mixture Of Volatile Organic Compounds Research Articles

Investigation the impact of using the recess air bio-filter (TBAB) with integrated system of a cyclic 2-recess adsorption/desorption unit for treatment of squander gas streams

In the chemical industry, fluctuations in influent concentrations and shifts in the composition of waste air make biofiltration a challenging technique. As a possible solution to the constraints of biofiltration technology, this research designs and implements an integrated system that includes a cyclic 2-bed adsorption/desorption unit and a trickling bed air biofilter (TBAB). The study's major goal was to keep the TBAB volatile organic compound (VOC) degradation performance stable and consistent over time. The studies were conducted on different TBABs with a single VOC exchange and a biomass control of periodic backwashing. Solvents that are routinely used in paint booths were examined as VOCs. Two aromatic chemicals (styrene and toluene) were investigated, as well as two aliphatic chemicals (methyl ethyl ketone (MEK) and methyl isobutyl ketone) (MIBK). While the production process rotated, our study duplicated VOC emission rotation in certain chemical sectors. When VOCs were switched to aromatics, the biofilter required an apparent re-acclimation period, according to the results. The second phase looked at two different combinations of these VOCs in two separate TBAB trains with a step change in influent concentration. In the third phase, the buffering performance of a cyclic 2-bed adsorption unit was tested for a feeding composition based on an EPA industrial emission report under a square wave of fluctuating conditions. The VOC mixture was treated in the fourth step with an integrated system that includes two cyclic adsorption/desorption beds as well as TBAB. When compared to the control unit, the integrated system was able to achieve high steady performance, according to the studies' findings. Lastly, researchers looked at the microbial communities of the biofilters employed in the VOC interchange and VOC mixing studies. The interchange of VOCs demonstrated a steady transition in microbial diversity. The community structure of VOC mixes demonstrated a significant degree of independence from the component content.

Co-Treatment with Single and Ternary Mixture Gas of Dimethyl Sulfide, Propanethiol, and Toluene by a Macrokinetic Analysis in a Biotrickling Filter Seeded with Alcaligenes sp. SY1 and Pseudomonas Putida S1

The biotrickling filter (BTF) treatment is an effective way of dealing with air pollution caused by volatile organic compounds (VOCs). However, this approach is typically used for single VOCs treatment but not for the mixtures of VOC and volatile organic sulfur compounds (VOSCs), even if they are often encountered in industrial applications. Therefore, we investigated the performance of BTF for single and ternary mixture gas of dimethyl sulfide (DMS), propanethiol, and toluene, respectively. Results showed that the co-treatment enhanced the removal efficiency of toluene, but not of dimethyl sulfide or propanethiol. Maximum removal rates (rmax) of DMS, propanethiol and toluene were calculated to be 256.41 g·m−3·h−1, 204.08 g·m−3·h−1 and 90.91 g·m−3·h−1, respectively. For a gas mixture of these three constituents, rmax was measured to be 114.94 g·m−3·h−1, 104.17 g·m−3·h−1 and 99.01 g·m−3·h−1, separately. Illumina MiSeq sequencing analysis further indicated that Proteobacteria and Bacteroidetes were the major bacterial groups in BTF packing materials. A shift of bacterial community structure was observed during the biodegradation process.

Detection of binary and ternary mixtures of volatile organic compounds using quartz tuning fork based sensor array

Polymer modified Quartz tuning fork based sensors are a versatile replacement for the conventional sensors available in the market for the development of sensor array for electronic nose applications. However, there is not enough work towards detection of mixture of analytes using these sensors. In this work, a sensor array is developed to detect mixture of styrene, propylbenzene and acetone. Based on the working principle of the sensor, parameters like recovery time, response time, and frequency shift, among others, are utilized for data classification of the sensor response. The data collected from the sensor is used to classify the several groups using ensemble classifier, where, support vector machines, k-nearest neighbour and artificial neural network participated as the voting algorithms. Initially, the classifier was able to make prediction with approximately 93% accuracy. After modification in the prediction process where classifier was trained in a progressive manner, in which it predicted only if the data point belonged to mixture or not and subsequently, if it belonged to binary or ternary mixture. This improved the overall accuracy to 98%. The work demonstrate that the combination of QTF sensor array and a suitable classifier can be used to detect binary and ternary mixtures and therefore, can be used for several applications of electronic nose.

Comparison of the Fruit Volatile Profiles of Five Muscadine Grape Cultivars (Vitis rotundifolia Michx.) Using HS-SPME-GC/MS Combined With Multivariate Statistical Analysis.

Fruit aromas are composed of a complex mixture of volatile organic compounds, which are essential attributes associated with the overall flavor and consumer preference. Muscadine grape (MG; Vitis rotundifolia Michx.) is an aroma-dense fruit crop. However, there is very scarce information on its volatile profiles. In this study, the volatile constituents of five newly introduced MG cultivars, including Alachua, Carlos, Fry, Granny Val, and Noble, were profiled using headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC/MS) combined with multivariate statistical analysis. A total of 44 compounds, including esters, aldehydes, alcohols, fatty acids, terpenes, ketones, and furan, were identified and relatively quantified. Principal component analysis (PCA) and partial least-squares discriminant analysis (PLS-DA) evidently discriminated against the five MG cultivars based on their volatile profiles. The specific volatiles that contributed the most to this discrimination were highlighted. Geraniol and cinnamyl alcohol were demonstrated to be essential for characterizing the Alachua MG cultivar, whereas ethyl trans-2-butenoate and propyl acetate were shown to be important compounds to characterize the Noble MG cultivar. The results further showed that 2-Ethyl-1-hexanol, (Z)-3-hexenal, and (E)-2-hexenol were closely related to Carlos, Fry, and Granny Val cultivars, respectively. This investigation is the first in-depth exploration of the volatile profiles of the aroma-dense muscadine grape, which is essential for future genetic or biotechnological improvements to attain a cultivar with the desired flavor.

Applications and Limitations of Quantifying Speciated and Source-Apportioned VOCs with Metal Oxide Sensors

While low-cost air quality sensor quantification has improved tremendously in recent years, speciated hydrocarbons have received little attention beyond total lumped volatile organic compounds (VOCs) or total non-methane hydrocarbons (TNMHCs). In this work, we attempt to use two broad response metal oxide VOC sensors to quantify a host of speciated hydrocarbons as well as smaller groups of hydrocarbons thought to be emanating from the same source or sources. For sensors deployed near oil and gas facilities, we utilize artificial neural networks (ANNs) to calibrate our low-cost sensor signals to regulatory-grade measurements of benzene, toluene, and formaldehyde. We also use positive matrix factorization (PMF) to group these hydrocarbons along with others by source, such as wet and dry components of oil and gas operations. The two locations studied here had different sets of reference hydrocarbon species measurements available, helping us determine which specific hydrocarbons and VOC mixtures are best suited for this approach. Calibration fits on the upper end reach above R2 values of 0.6 despite the parts per billion (ppb) concentration ranges of each, which are magnitudes below the manufacturer’s prescribed detection limits for the sensors. The sensors generally captured the baseline trends in the data, but failed to quantitatively estimate larger spikes that occurred intermittently. While compounds with high variability were not suited for this method, its success with several of the compounds studied represents a crucial first step in low-cost VOC speciation. This work has important implications in improving our understanding of the links between health and environment, as different hydrocarbons will have varied consequences in the human body and atmosphere.

Thermocatalytic oxidation of a three-component mixture of volatile organic compounds by a titanium dioxide-supported platinum catalyst

To gain a better knowledge for efficient treatment of volatile organic compounds (VOCs), a series of experiments were carried out to assess the potential of titanium dioxide (TiO2)-supported platinum (Pt) catalyst (Pt/TiO2) in low-temperature catalytic oxidation of formaldehyde (FA), acetaldehyde (AA), and toluene (T) (10–100 ppm range) both individually and as a mixture. Accordingly, 100% mineralization of FA (50–200 ppm), AA (10 ppm), and T (10 ppm) was achieved by 1%-Pt/TiO2-R (‘R’ suffix for reduction pretreatment on the catalyst) at 30, 190, and 160 °C, respectively. The carbon dioxide (CO2) yield was used to assess the extent of VOC mineralization in air (as the carrier gas at a flow rate of 0.2 L atm min ̶ 1). Their conversion efficiency was lowered with increases in the pollutant concentration or decreases in the bed mass. Furthermore, the reaction intermediates and catalytic pathways were assessed based on in-situ diffuse reflectance infrared Fourier transform spectroscopy. This study offers valuable insights into the interactive roles between process variables in the low-temperature thermocatalytic oxidation of single and/or multi-component gaseous VOC systems and into the effects of such variables on the overall catalytic performance.

Enhanced Selectivity in Volatile Organic Compound Gas Sensors Based on ReS2-FETs under Light-Assisted and Gate-Bias Tunable Operation.

Using a single-device two-dimensional (2D) rhenium disulfide (ReS2) field-effect transistor (FET) with enhanced gas species selectivity by light illumination, we reported a selective and sensitive detection of volatile organic compound (VOC) gases. 2D materials have the advantage of a high surface-area-to-volume ratio for high sensitivity to molecules attached to the surface and tunable carrier concentration through field-effect control from the back-gate of the channel, while keeping the top surface open to the air for chemical sensing. In addition to these advantages, ReS2 has a direct band gap also in multilayer cases, which sets it apart from other transition-metal dichalcogenides (TMDCs). We take advantage of the effective response of ReS2 to light illumination to improve the selectivity and gas-sensing efficiency of a ReS2-FET device. We found that light illumination modulates the drain current response in a ReS2-FET to adsorbed molecules, and the sensing activity differs depending on the gas species used, such as acetone, ethanol, and methanol. Furthermore, wavelength and carrier density rely on certain variations in light-modulated sensing behaviors for each chemical. The device will distinguish the gas concentration in a mixture of VOCs using the differences induced by light illumination, enhancing the selectivity of the sensor device. Our results shed new light on the sensing technologies for realizing a large-scale sensor network in the Internet-of-Things era.

Compound-specific carbon isotope analysis of volatile organic compounds in complex soil extracts using purge and trap concentration coupled to heart-cutting two-dimensional gas chromatography–isotope ratio mass spectrometry

Compound-specific carbon isotope analysis (CSIA) is a powerful tool to track the origin and fate of organic subsurface contaminants including petroleum and chlorinated hydrocarbons and is typically applied to water samples. However, soil can form a significant contaminant reservoir. In soil samples, it can be challenging to recover sufficient amounts of volatile organic compounds (VOC) to perform CSIA. Soil samples often contain complex contaminant mixtures and gas chromatography combustion isotope ratio mass spectrometry (GC-C-IRMS) is highly dependent on good chromatographic separation due to the conversion to a single analyte. To extend the applicability of CSIA to complex volatile organic compound mixtures in soil samples, and to recover sufficient amounts of target compounds for carbon CSIA, we compared two soil extraction solvents, tetraglyme (TGDE) and methanol, and developed a heart-cutting two-dimensional GC-GC-C-IRMS method. We used purge & trap concentration of solvent-water mixtures to increase the amount of analyte delivered to the column and thus lower method detection limits. We optimized purge & trap and chromatographic parameters for twelve target compounds, including one suffering from poor purge efficiency. By using a 30 m thick-film non-polar column in the first and a 15 m polar column in the second dimension, we achieved good chromatographic separation for the target compounds in difficult matrices and high accuracy (trueness and precision) for carbon isotopic analysis. Tetraglyme extraction was shown to offer advantages over methanol for purge & trap concentration, leading to lower target compound method detection limits for CSIA of soil samples. The applicability of the developed method was demonstrated for a case study on soil extracts from a former manufacturing facility. Our approach extends the applicability of CSIA to an important matrix that often controls the long-term fate of contaminants in the subsurface.

Biyolojik mücadelede fungal uçucu organik bileşiklerin (FVOCs) rolü

Organisms such as bacteria, fungi, viruses, and nematodes cause yield and quality loss in agricultural production. Especially the control of fungal pathogens is challenging. The fact that chemical pesticides used in the control of these pathogens are not environmentally friendly, increases the importance of alternative methods such as the use of biopesticides. Biopesticides that are not relatively harmful to human health and the environment are generally secondary metabolites from plants, viruses, bacteria and fungi. Fungi produce various mixtures of volatile organic compounds (VOCs). More than 300 different fungal VOCs including aldehydes, alcohols, benzene derivatives, phenols, heterocycles, hydrocarbons, ketones, cyclohexanes, thioesters, and thioalcohols have been described. The interaction between fungal VOCs and plant pathogens pose an ecofriendly alternative to chemical pesticides. Researches have shown that fungal VOCs can be used effectively with their inhibitory or repellent aspect against the plant pathogens and insect pests as a biopesticide. In this review, the possibilities of using fungal VOCs against different plant diseases and pests as an substitute to chemical pesticides within the scope of biological control are summarized.

Classification and Identification of Essential Oils from Herbs and Fruits Based on a MOS Electronic-Nose Technology

The frequent occurrence of adulterated or counterfeit plant products sold in worldwide commercial markets has created the necessity to validate the authenticity of natural plant-derived palatable products, based on product-label composition, to certify pricing values and for regulatory quality control (QC). The necessity to confirm product authenticity before marketing has required the need for rapid-sensing, electronic devices capable of quickly evaluating plant product quality by easily measurable volatile (aroma) emissions. An experimental MAU-9 electronic nose (e-nose) system, containing a sensor array with 9 metal oxide semiconductor (MOS) gas sensors, was developed with capabilities to quickly identify and classify volatile essential oils derived from fruit and herbal edible-plant sources. The e-nose instrument was tested for efficacy to discriminate between different volatile essential oils present in gaseous emissions from purified sources of these natural food products. Several chemometric data-analysis methods, including pattern recognition algorithms, principal component analysis (PCA), and support vector machine (SVM) were utilized and compared. The classification accuracy of essential oils using PCA, LDA and QDA, and SVM methods was at or near 100%. The MAU-9 e-nose effectively distinguished between different purified essential oil aromas from herbal and fruit plant sources, based on unique e-nose sensor array responses to distinct, essential-oil specific mixtures of volatile organic compounds (VOCs).

Indoor pet allergen exposures modify the effects of chemical air pollutants on respiratory symptoms

SETTING: Indoor volatile organic compound (VOC) levels, which are generally correlated with each other, may have an additive or synergistic effect on health. VOC synergy with allergens is a suspected mechanism affecting respiration.OBJECTIVE: To determine the effect of exposure to interactions between VOCs and allergens on respiratory symptoms in individuals aged ≥15 years.DESIGN: A national cross-sectional survey measured 20 VOCs and dog and cat aeroallergens in 490 main residential dwellings in France. A standardised questionnaire was used to elicit responses on respiratory conditions in 1012 inhabitants. Four VOC factor scores (linear combinations of VOCs) were generated using principal component analysis. In order to take into account the phenomenon of multi-pollution, marginal models were used to model the relationships between exposure to VOC mixture and respiratory conditions. Stratified models were used to examine the interaction between allergens and VOCs.RESULTS: The aromatic hydrocarbon score was associated with rhinitis and wheezing, the aliphatic hydrocarbon score with asthma and cough, the halogenated hydrocarbons with asthma, wheezing and rhinitis. Aldehydes and Can f1 had a significant synergistic effect on wheezing and rhinitis. Aliphatic hydrocarbons had an antagonist effect with Can f1 on wheezing.CONCLUSION: Our data support evidence of adverse effects of exposure to VOC mixture on respiratory conditions; this effect is aggravated in the presence of pet allergens.

Inhibit the formation of toxic methylphenolic by-products in photo-decomposition of formaldehyde–toluene/xylene mixtures by Pd cocatalyst on TiO2

Photocatalytic removal of single volatile organic compounds (VOCs) has been widely investigated; however, photodecomposition of VOC mixtures has been rarely addressed, which may bring safety doubts in indoor air purification due to possible formation of harmful compounds. Here we show that in photocatalytic oxidation of formaldehyde–toluene and formaldehyde–xylene mixtures, the introduction of Pd cocatalyst on TiO2 photocatalyst successfully inhibits the formation of toxic methylphenols, thus promoting the complete mineralization of VOC mixtures into CO2via the harmless benzaldehyde intermediates. Mechanistic analysis reveals that the loading of Pd cocatalyst effectively removes the inherent surface −OH groups of TiO2, which significantly promotes the activation of O2 into OH radicals. The Pd cocatalyst also directs the OH radicals to attack the methyl group instead of the aromatic ring for the formation of benzaldehyde and its further oxidation to CO2, thus yielding a better overall photocatalytic performance.

Virtual sensor array based on MXene for selective detections of VOCs

Abstract Two-dimensional transition metal carbides/nitrides, known as MXenes, have recently received significant attention for gas sensing applications. However, MXenes have strong adsorption to many types of volatile organic compounds (VOCs), and therefore gas sensors based on MXenes generally have low selectivity and poor performance in mixtures of VOCs due to cross-sensitivity issues. Herein, we developed a Ti3C2Tx-based virtual sensor array (VSA) which allows both highly accurate detection and identification of different VOCs, as well as concentration prediction of the target VOC in variable backgrounds. The VSA’s responses from the broadband impedance spectra create a unique fingerprint of each VOC without a need for changing temperatures. Based on the methodologies of principal component analysis and linear discrimination analysis, we demonstrate highly accurate identifications for different types of VOCs and mixtures using this MXene based VSA. Furthermore, we demonstrate an accuracy of 93.2% for the prediction of ethanol concentrations in the presence of different concentrations of water and methanol. The high level of identification and concentration prediction shows a great potential of MXene based VSA for detection of VOCs of interest in the presence of known and unknown interferences.

Exposure to volatile organic compounds – acrolein, 1,3-butadiene, and crotonaldehyde – is associated with vascular dysfunction

BackgroundCardiovascular disease (CVD) is the leading cause of mortality worldwide. Exposure to air pollution, specifically particulate matter of diameter ≤2.5 μm (PM2.5), is a well-established risk factor for CVD. However, the contribution of gaseous pollutant exposure to CVD risk is less clear. ObjectiveTo examine the vascular effects of exposure to individual volatile organic compounds (VOCs) and mixtures of VOCs. MethodsWe measured urinary metabolites of acrolein (CEMA and 3HPMA), 1,3-butadiene (DHBMA and MHBMA3), and crotonaldehyde (HPMMA) in 346 nonsmokers with varying levels of CVD risk. On the day of enrollment, we measured blood pressure (BP), reactive hyperemia index (RHI – a measure of endothelial function), and urinary levels of catecholamines and their metabolites. We used generalized linear models for evaluating the association between individual VOC metabolites and BP, RHI, and catecholamines, and we used Bayesian Kernel Machine Regression (BKMR) to assess exposure to VOC metabolite mixtures and BP. ResultsWe found that the levels of 3HPMA were positively associated with systolic BP (0.98 mmHg per interquartile range (IQR) of 3HPMA; CI: 0.06, 1.91; P = 0.04). Stratified analysis revealed an increased association with systolic BP in Black participants despite lower levels of urinary 3HPMA. This association was independent of PM2.5 exposure and BP medications. BKMR analysis confirmed that 3HPMA was the major metabolite associated with higher BP in the presence of other metabolites. We also found that 3HPMA and DHBMA were associated with decreased endothelial function. For each IQR of 3HPMA or DHBMA, there was a −4.4% (CI: −7.2, −0.0; P = 0.03) and a −3.9% (CI: −9.4, −0.0; P = 0.04) difference in RHI, respectively. Although in the entire cohort the levels of several urinary VOC metabolites were weakly associated with urinary catecholamines and their metabolites, in Black participants, DHBMA levels showed strong associations with urinary norepinephrine and normetanephrine levels. DiscussionExposure to acrolein and 1,3-butadiene is associated with endothelial dysfunction and may contribute to elevated risk of hypertension in participants with increased sympathetic tone, particularly in Black individuals.

Continuous flow pulsed power plasma reactor for the treatment of aqueous solution containing volatile organic compounds and real pharmaceutical wastewater

The degradation of four recalcitrant and toxic VOCs (volatile organic compounds) present in pharmaceutical wastewater was studied using a continuous flow plasma reactor, along with evaluating its potential for real effluent treatment. The wastewater was sprayed into the plasma zone of the reactor, and it was re-circulated for better performance. The effect of different HRTs (hydraulic retention time) and initial concentrations of VOCs on the degradation efficiency were evaluated. In continuous reactor, complete removal of 200 mg/L of chloroform, chlorobenzene, and toluene was achieved at a HRT of 33.3 min, with an energy consumption of 22.4 kWh/m3. The study on the effect of different inlet loading rates of VOCs on elimination capacity showed that, the removal was limited initially by diffusion of reactive species and at higher loads, it was limited by insufficient amount of reactive species produced. During degradation of VOC mixture, more than 90% removal of chloroform, chlorobenzene and toluene was achieved at HRT of 33.3 min, and the TOC removal was 78.3%. The degradation efficiency of VOC mixture reduced slightly compared to that of individual compounds, due to insufficient amount of reactive species produced. The COD and BOD removal achieved after 140 min of direct plasma treatment of real pharmaceutical wastewater in batch reactor was 92.7% and 95.2%, respectively. Coagulation pre-treatment did not have a significant effect on the plasma treatment of real wastewater. When pharmaceutical effluent treatment was carried out in continuous flow reactor, 91.8% COD removal, 90.9% BOD removal and more than 90% degradation of all VOCs were achieved at a HRT of 150 min. Plasma treatment alone was capable of effectively treating the real pharmaceutical wastewater without any pre-treatment.

Volatile Organic Compounds Produced by Human Pathogenic Fungi Are Toxic to Drosophila melanogaster.

Volatile organic compounds (VOCs) are low molecular mass organic compounds that easily evaporate at room temperature. Fungi produce diverse mixtures of VOCs, some of which may contribute to "sick building syndrome," and which have been shown to be toxigenic in a variety of laboratory bioassays. We hypothesized that VOCs from medically important fungi might be similarly toxigenic and tested strains of Aspergillus fumigatus, Candida albicans, Cryptococcus neoformans, Cryptococcus gattii, and Saccharomyces cerevisiae in a Drosophila melanogaster eclosion bioassay. Fungi were grown in a shared microhabitat with third instar larvae of D. melanogaster such that there was no physical contact between flies and fungi. As the flies went through metamorphosis, the numbers of larvae, pupae, and adults were counted daily for 15 days. After 8 days, ~80% of controls had eclosed into adults and after 15 days the controls yielded 96-97% eclosion. In contrast, eclosion rates at 8 days were below 70% for flies exposed to VOCs from six different A. fumigatus strains; the eclosion rate at 15 days was only 58% for flies exposed to VOCs from A. fumigatus strain SRRC 1607. When flies were grown in a shared atmosphere with VOCs from S. cerevisiae, after 15 days, 82% of flies had eclosed into adults. Exposure to the VOCs from the medically important yeasts Candida albicans, Cryptococcus neoformans, and Cryptococcus gattii caused significant delays in metamorphosis with eclosion rates of 58% for Candida albicans, 44% for Cryptococcus neoformans, and 56% for Cryptococcus gattii. Using gas chromatography-mass spectrometry, the VOCs from the most toxic and least toxic strains of A. fumigatus were assayed. The two most common VOCs produced by both strains were 1-octen-3-ol and isopentyl alcohol; however, these compounds were produced in 10-fold higher concentrations by the more toxic strain. Our research demonstrates that gas phase compounds emitted by fungal pathogens may have been overlooked as contributing to the pathogenicity of medically important fungi and therefore deserve more scrutiny by the medical mycology research community.

Analysis of volatile oxidized oligomers from polyolefins by off-line normal phase high performance liquid chromatography and one-dimensional and comprehensive two-dimensional gas chromatography

The off-line coupled high performance liquid chromatography - gas chromatography - mass spectrometry (HPLC-GC–MS) was used for the analysis of oxidized oligomers from polyolefins. In order to optimize the HPLC fractionation method, a complex substance mixture of volatile organic compounds (VOC) from the provoked thermal oxidation of polyethylene (PE) was investigated. The fractionation was performed by normal phase HPLC, which separated the analytes according to their polarity. The seven obtained fractions were transferred off-line to the GC–MS. By means of fractionation nearly all coelutions present in the total extract could be avoided, which facilitated the identification of substances considerably. In addition, a separation according to functional moieties of substances was achieved, resulting in homologous series of compounds in the individual fractions: polyolefin oligomeric hydrocarbons (POH) in fraction 1, aldehydes and 7-, 6-, and 5-ketones in fraction 3, 2-ketones and alkenals in fraction 4, lactones and carboxylic acids in fraction 5, 1- and 2-alcohols in fraction 6 and diones in fraction 7, respectively. In this work, 7-, 6- and 5-ketones, δ-lactones, 2-alcohols and diones were identified for the first time in oxidized PE. Verification of fractionation and substance identification was done by comprehensive two-dimensional gas chromatography - time of flight - mass spectrometry (GCxGC-TOF-MS) measurements as well as off-line HPLC-GC–MS measurements using a mixture of reference substances. The fractionation approach was applied for the analysis of a commercial PE film after melt flow extrusion. POH were eluted in fraction 1, while n-aldehydes (with a carbon chain length of C11-18) were identified in fraction 3 and 2-ketones (C13-15) in fraction 4. The amounts of the individual detectable oxidized oligomers were estimated semi-quantitatively to range from 10 – 170 µg/kg.

Viscosity and liquid–liquid phase separation in healthy and stressed plant SOA

Molecular composition, viscosity, and phase state were investigated for secondary organic aerosol derived from synthetic mixtures of volatile organic compounds representing emissions from healthy and aphid-stressed Scots pine trees.

Identifying Binary Mixtures of Volatile Organic Compounds With Isomeric Components Using a Single Thermal Shock-Induced Generic SnO2 Gas Sensor

Identifying the components and their relative proportions in the binary mixtures of the structurally similar Volatile Organic Compounds (VOCs) are required for many applications. In this work, the binary vapor mixtures of VOCs with isomeric components at variable combined concentrations ranging from 200 to 2500 ppm are discriminated using a single generic tin oxide gas sensor. Sharp fluctuations in the pellet temperature bring in more valuable analyte nature-related information into the sensor's response patterns, which can be extracted and used for discriminating among complex mixtures. The classic staircase voltage waveform fails to produce the abrupt variations in the pellet temperature facilitated via the thermal shock induction method applied for the virtual array formation out of a single tin oxide chemiresistor. Linear discriminant analysis is applied after preprocessing and feature selection of the sensor response patterns. Two simple classifiers operating based on the Euclidean distance in the feature space are utilized for analyte classification. The recognitions of binary vapor mixtures of 1-propanol, 2-propanol, 1-butanol, and 2-butanol are demonstrated as examples. A total of 546 individual experiments are carried out to confirm the accuracy of the performance; all the binary test mixtures are identified correctly; with 2.3% of error in compositions determination. The experiments are satisfactorily repeated in the form of independent work sessions within a 1-month time interval to represent the repeatability of the response patterns. The thermal shock induction appears as a replacement for the sensor arrays which suffer from the multi-dimensional drift of the array components.

Blood plasma levels of biomarkers of liver status and lipid profile among nail technicians occupationally exposed to low-level mixture of volatile organic compounds

PurposeNail technicians (NTs) are exposed to a low-level mixture of volatile organic solvents (VOCs), yet the health hazards related to such exposure are unknown. This study thus aimed to compare the blood plasma levels of selected biomarkers related to liver status and lipid profile among occupationally exposed NTs and unexposed controls. Associations between out-of-normal-range levels of such biomarkers and occupational exposure to VOCs mixture have also been investigated.MethodsThe study enrolled 145 female NTs and 152 unexposed controls. Biochemical analyses were performed using spectrophotometric assays and obtained data were analyzed using general linear model and Poisson regression modelling adjusted to multiple confounders.ResultsCompared to controls, NTs presented significantly increased plasma activities of ALT (2.04 ± 0.63 ln-U/l vs. 1.25 ± 0.71 ln-U/l; p < 0.0001) and AST (2.73 ± 0.25 ln-U/l vs. 2.08 ± 0.95 ln-U/l; p < 0.0001), and significantly increased plasma levels of TG (4.38 ± 0.53 ln-mg/dl vs. 4.21 ± 0.42 ln-mg/dl; p < 0.05) and TC/HDL ratio (1.18 ± 0.36 vs. 1.02 ± 0.27; p < 0.0005). Plasma levels of HDL were significantly lower among NTs (4.02 ± 0.29 ln-mg/dl vs. 4.21 ± 0.26 ln-mg/dl; p < 0.0001). Moreover, NTs were found to present significantly increased risk of occurrence of clinically relevant plasma HDL levels below 3.91 ln-mg/dl (i.e., 50 mg/dl; RR = 1.58, 95% CI 1.07–2.32, p < 0.05), as well as increased risk of clinically relevant TC/HDL ratio above the normal range limit of 3.5 (RR = 1.68, 95% CI 1.19–2.35, p < 0.005), as compared to unexposed controls.ConclusionNail technicians are subject to adverse changes in selected plasma biomarkers related to liver functions, some of which may be of clinical relevance.