VOC Profiles Research Articles

Analysis of VOCs in Urine Samples Directed towards of Bladder Cancer Detection.

Bladder cancer is one of most common types of cancer diagnosed in the genitourinary tract. Typical tests are costly and characterized by low sensitivity, which contributes to a growing interest in volatile biomarkers. Head space solid phase microextraction (SPME) was applied for the extraction of volatile organic compounds from urine samples, and gas chromatography time of flight mass spectrometry (GC×GC TOF MS) was used for the separation and detection of urinary volatiles. A cohort of 40 adult patients with bladder cancer and 57 healthy persons was recruited. Different VOC profiles were obtained for urine samples taken from each group. Twelvecompounds were found only in the samples from theBC group.The proposed candidate biomarkers are butyrolactone; 2-methoxyphenol; 3-methoxy-5-methylphenol; 1-(2,6,6-trimethylcyclohexa-1,3-dien-1-yl)-2-buten-1-one; nootkatone and 1-(2,6,6-trimethyl-1-cyclohexenyl)-2-buten-1-one.Since most of the studies published in the field are proving the potential of VOCs detected in urine samples for the screening and discrimination of patients with bladder cancer from healthy, but rarely presenting the identity of proposed biomarkers, our study represents a novel approach.

From Hops to Craft Beers: Production Process, VOCs Profile Characterization, Total Polyphenol and Flavonoid Content Determination and Antioxidant Activity Evaluation

In this work, selections of seven international hop varieties and three craft beers obtained from them were analyzed by SPME-GC/MS techniques with the aim to describe their volatile chemical profile. The brewing process was also reported. Furthermore, the hop extracts and beers were investigated to determine their flavonoid and polyphenol content and to evaluate their antioxidant power by DPPH and ABTS assays. The findings showed the presence of compounds belonging to different chemical classes such as monoterpenes, sesquiterpenes, alcohols, esters and fatty acids. In particular, sesquiterpenes were the main compounds with β-caryophyllene (from 1.7 to 16.2%) and humulene (from 10.8 to 43.9%) as the major components in all varieties of dried hop cones investigated. On the contrary, with the exception for the Pacific sample, monoterpenes were the class of compounds that were more abundant in the hop extracts and, among these, β-myrcene appeared to be the predominant constituent (from 31.8 to 71.4%). Regarding the craft beers obtained by adding these hop varieties, some differences in the qualitative and quantitative volatile composition have been found. All hop samples showed a high scavenging potential against both radicals. In the case of DPPH, the obtained IC50 values ranged from 0.027 to 0.047 mg/mL while they varied between 0.023 and 0.134 mg/mL by the ABTS assay. A positive correlation was found with polyphenol and flavonoid contents. Among beer samples, ACD was the richest one in polyphenols (292.0 mg GAE/100 mL beer) and flavonoids (5.8 mg QE/100 mL beer) and the most powerful against DPPH• and ABTS•+ radicals with IC50 values equal to 4.969 and 0.198 v/v%, respectively.

Influence of Drying Methods and Vacuum Impregnation on Selected Quality Factors of Dried Sweet Potato

A comparative study was conducted on the effect of vacuum impregnation and drying methods on the production of dried sweet potatoes with high bioactivity. The present study determined the quality and physicochemical properties of dried sweet potato depending on the used impregnating solutions. Sweet potatoes were pretreated in freshly squeezed onion (O) and kale (K) juice, onion and kale (OK) mixture (1:1), and sodium chloride solution. Vacuum impregnation (VI) was carried out under reduced pressure (6 kPa) for 2 min, after which the impregnating solution was dispensed and maintained under vacuum for 4 min. Sweet potato slices were dried using vacuum drying (VD) and freeze drying (FD) methods. Higher content of polyphenols, carotenoids, and chlorophyll, as well as increased antioxidant capacity and higher VOC profile, were recorded for the dried products obtained using the sublimation method. The use of vacuum impregnation reduced the hardness of the products and other textural characteristics, such as cohesiveness, springiness, and gumminess. Furthermore, we found that vacuum impregnation pretreatment was a beneficial method for improving the characteristics of dried vegetables. The highest content of phenolics, carotenoids, and chlorophylls in dried sweet potatoes were recorded when samples were impregnated with onion and kale juice. For the fresh sweet potato, the highest contribution in VOC composition had phenylacetaldehyde (44.90%), (E)-2-octen-1-al (9.43%), and benzaldehyde (8.18%), respectively. The interesting content of VOC profile compounds in dried sweet potatoes was recorded when samples were impregnated with kale juice.

Physicochemical properties, antioxidant content, volatile organic compounds and sensory profile of cocoa beans fermented with yeast starter cultures

This study determined the influence of selected yeast starters on the antioxidant content, volatile organic compounds and sensory qualities of fermented cocoa beans. Cocoa beans fermented with Hanseniaspora thailandica (MH979675), Pichia kudriazevii (MH979681), or a mixture of both species in fermentation (20 kg) were highly reproducible based on the physicochemical parameters (temperature, pH of nibs, fermentation index and cut test). The usage of H. thailandica improved the total polyphenols content of cocoa beans with fermentation index around 1.24 and 1.33. The correlation analyses suggested that phenolics and flavonoids compounds may not be the main constituents that led to the antioxidant activities of the fermented samples. Principal Component Analysis showed distinct differences in VOC profiles between spontaneous and fermentation using yeast. Sweet and spicy notes were only found in sample fermented with yeast. The inoculation of yeast in fermentation influenced the sensorial and antioxidant properties of cocoa beans.

The Relationship Between Exhaled Volatile Organic Compounds And Respiratory Function In Response To Ultra-endurance Exercise

PURPOSE: To date, limited studies have examined exhaled VOC profiles in response to a physiologic stressor such as ultra-endurance exercise. Accordingly, this study evaluated VOC production in exhaled breath and the relationship to respiratory function in response to running an ultramarathon. METHODS: Breath samples (VOC Breath Biopsy, Owlstone Medical, Cambridge UK) were collected from 29 ultra-endurance runners before and after participating in either the 2019 Ultra-Trail du Mont-Blanc (171 km) or Courmayeur-Champex-Chamonix (100 km) ultramarathon. Additionally, subjects performed pulmonary function tests (PFT) before and after the race. A Wilcoxon signed-rank test was performed to evaluate changes in the intra-participant exhaled VOCs between the pre- and post-race breath samples. A Pearson Correlation Coefficient was used to determine any correlations between changes in exhaled VOCs and PFTs. Only participants who performed PFTs and “breath biopsies” pre- and post-race were included in the analysis (n = 23). RESULTS: Participants completed the ultra-marathons on average in 29.3 ± 12.1 hours. In total, 811 unique VOCs were measured and studied for differences between the pre- and post-race participant breath samples, with 63 having significant (P < 0.05) changes pre to post-race (12 decreased, 51 increased). Of these, 10 had identities assigned from the Breath Biopsy Laboratory. These VOCs were predominately comprised of methyl- and ethyl-containing compounds (n = 9) and ketones (n = 6), which possibly relate to inflammation or metabolic shifts. Four of the identified VOCs (Isopropyl Alcohol, Methyl Vinyl Ketone, Hexamethyldisiloxane, and 2, 3-Butanediol) correlated significantly to changes in inspiratory volumes and flows, possibly linking these VOCs to a reduction in lung function. For example, increases in 2,3-Butanediol were correlated to decreases in forced inspiratory vital capacity (R = -0.51, P = 0.01), FIV1(R = -0.50, P = 0.02), and peak inspiratory flow rate (R = -0.047, P = 0.02). CONCLUSIONS: These data suggest there are exhaled VOCs of biological origin that may significantly change in response to ultra-endurance exercise. Additionally, the magnitude of change in a subset of these VOCs may correspond to decrements in respiratory function resulting from this extreme physical activity.

Volatile composition and enantioselective analysis of chiral terpenoids in Tokaj varietal wines

The present work compares VOC profiles of 37 Tokaj varietal wines produced from Furmint, Lipovina and Muškát žltý grape varieties determined by SPME-GC–MS. The identified VOCs underwent treatment using one-way ANOVA and PCA for determination of compounds capable to distinguish wines based on grapevine variety. The presence of high concentration of terpenoids was characteristic for Muškát žltý wines, while Furmint and Lipovina expressed quite high similarity, nevertheless Lipovina was characterized by higher relative concentration of 1,1,6-trimethyl-1,2-dihydronaphtalene. Enantioselective analysis of the dominant terpenoids (limonene, linalool, hotrienol and α-terpineol) was performed by heartcut-2D-GC: R form was dominant for limonene and linalool and S enantiomer for hotrienol and α-terpineol. Statistical analysis (ANOVA) confirmed R-linalool as the most significant compound responsible for the main differences between studied varietal wines. LDA identified both total linalool and R-linalool as the only significant (p ≤ 0.05) sorting keys to distinguish investigated varietal wines. Both models allow perfect distinguishing of Muškát žltý from Lipovina and Furmint (p ≤ 0.05) with posterior probability of re-identification 100% but low distinction of Lipovina and Furmint from each other. The probability of posterior re-identification of Lipovina raised from 76.9 to 84.6% and total probability from 86.5 to 89.2% when using dominant enantiomer concentration as sorting variable.

A two-tiered system of analysis to tackle rice fraud: The Indian Basmati study

Demand for high quality Basmati rice has increased significantly in the last decade. This commodity is highly vulnerable to fraud, especially in the post COVID-19 era. A unique two-tiered analytical system comprised of rapid on-site screening of samples using handheld portable Near-infrared NIR and laboratory confirmatory technique using a Head space gas chromatography mass spectrometry (HS-GC-MS) strategy for untargeted analysis was developed. Chemometric models built using NIR data correctly predicted nearly 100% of Pusa 1121 and Taraori, two high value types of Basmati, from potential adulterants. Furthermore, rice VOC profile fingerprints showed very good classification (R2 >0.9, Q2 > 0.9, Accuracy > 0.99) for these high quality Basmati varieties from potential adulterant varieties with aldehydes identified as key VOC marker compounds. Using a two-tiered system of a rapid method for on-site screening of many samples alongside a laboratory-based confirmatory method can classify Basmati rice varieties, protecting the supply chain from fraud.

Probabilistic topic modelling in food spoilage analysis: A case study with Atlantic salmon (Salmo salar)

Probabilistic topic modelling is frequently used in machine learning and statistical analysis for extracting latent information from complex datasets. Despite being closely associated with natural language processing and text mining, these methods possess several properties that make them particularly attractive in metabolomics applications where the applicability of traditional multivariate statistics tends to be limited. The aim of the study was thus to introduce probabilistic topic modelling – more specifically, Latent Dirichlet Allocation (LDA) – in a novel experimental context: volatilome-based (sea) food spoilage characterization. This was realized as a case study, focusing on modelling the spoilage of Atlantic salmon (Salmo salar) at 4 °C under different gaseous atmospheres (% CO2/O2/N2): 0/0/100 (A), air (B), 60/0/40 (C) or 60/40/0 (D). First, an exploratory analysis was performed to optimize the model tunings and to consequently model salmon spoilage under 100% N2 (A). Based on the obtained results, a systematic spoilage characterization protocol was established and used for identifying potential volatile spoilage indicators under all tested storage conditions. In conclusion, LDA could be used for extracting sets of underlying VOC profiles and identifying those signifying salmon spoilage, giving rise to an extensive discussion regarding the key points associated with model tuning and/or spoilage analysis. The identified compounds were well in accordance with a previously established approach based on partial least squares regression analysis (PLS). Overall, the outcomes of the study not only reflect the promising potential of LDA in spoilage characterization, but also provide several new insights into the development of data-driven methods for food quality analysis.

Fruit volatilome profiling through GC\u2009\xd7\u2009GC-ToF-MS and gene expression analyses reveal differences amongst peach cultivars in their response to cold storage

Peaches have a short shelf life and require chilling during storage and transport. Peach aroma is important for consumer preference and determined by underlying metabolic pathways and gene expression. Differences in aroma (profiles of volatile organic compounds, VOCs) have been widely reported across cultivars and in response to cold storage. However, few studies used intact peaches, or used equilibrium sampling methods subject to saturation. We analysed VOC profiles using TD-GC × GC-ToF-MS and expression of 12 key VOC pathway genes of intact fruit from six cultivars (three peaches, three nectarines) before and after storage at 1 °C for 7 days including 36 h shelf life storage at 20 °C. Two dimensional GC (GC × GC) significantly enhances discrimination of thermal desorption gas chromatography time-of-flight mass spectrometry (TD-GC-ToF-MS) and detected a total of 115 VOCs. A subset of 15 VOCs from analysis with Random Forest discriminated between cultivars. Another 16 VOCs correlated strongly with expression profiles of eleven key genes in the lipoxygenase pathway, and both expression profiles and VOCs discriminated amongst cultivars, peach versus nectarines and between treatments. The cultivar-specific response to cold storage underlines the need to understand more fully the genetic basis for VOC changes across cultivars.

Analysis of aroma-related volatile compounds affected by ‘Ginsen Makuwa’ genomic regions introgressed in ‘Vedrantais’ melon background

Volatile profile of melon fruit from 25 introgression lines (ILs), developed by introgressing specific genomic regions from the Japanese cultivar ‘Ginsen makuwa’ (MAK) into the ‘Charentais’ recurrent genetic background of the cultivar ‘Vedrantais’ (VED), was characterized in two environments. Fifty-seven VOCs were identified by purge and trap extraction followed by chromatography-mass spectrometry. IL population was also genotyped by GBS with 2,146 SNP distributed throughout the melon genome to tag MAK introgressions. The aromatic profiles of both parents and their hybrid suggested the dominance of MAK alleles. MAK introgressions in the VED background in general reduced the accumulation of VOCs in fruit, mainly alkyl esters and apocarotenoids. The environmental effect was remarkable, although some ILs showed a volatile profile stability in both environments. Some ILs with specific MAK introgressions displayed specific VOC profiles. The joint analysis of VOC profiles and GBS genotypes allowed for the identification of candidate genes, such as MELO3C024886, a 4-coumarate:CoA ligase which can be involved in the eugenol pathway, and other genes previously reported to be involved in melon VOCs production from fatty acids, aminoacids or carotenoids (CmLOX18, CmAAT, CmBAMT, CmCRTISO1), whose MAK alleles introgressed on VED genetic background might change the Charentais VOC profile. Additionally, some ILs showed changes in VOC profiles due to pleiotropic effects of changes in other traits, such as the low levels of apocarotenoids in the two green fleshed ILs (CmOrCmOr genotype), associated to the lack of carotenoid precursors, and the new ester profile of the ILs with altered ripening pattern (likely due to the introgression of the MAK NAC factor MELO3C012215). The information generated about the candidate regions and genes will be of interest for further genetic studies, to optimize the use of MAK genetic resources in melon breeding, and also to develop new lines with Charentais background and novel aroma profiles.

Electronic nose in discrimination of children with uncontrolled asthma

Measuring biomarkers (e.g. volatile organic compounds [VOCs]) in exhaled breath is an attractive approach to monitor airway inflammation in asthma and other lung diseases. Olfactive technology by electronic nose (e-Nose) has been applied to identify VOCs in exhaled breath. We compared e-Nose respiratory patterns in a pediatric cohort with asthma classificate children with different asthma control. This cross-sectional study involved 38 children: 28 with asthma and 10 healthy controls . The asthmatic patients were categorized as having controlled (AC), partially controlled (APC) or uncontrolled asthma (ANC) based on level of asthma symptom control according to Global Initiative for Asthma (GINA). Clinical exams, exhaled breath collection for generating e-Nose VOC profiles, and spirometry were performed. Exhaled breath samples were obtained using a commercial electronic nose (Cyranose 320; Smith Detections, Pasadena, CA, USA). The discriminative ability of breathprints were investigated by principal component analysis and penalized logistic regression. The e-Nose was able to discriminate between the CON (controls) + AC and the ANC + APC group with an area under the curve [AUC] of 0.85 (95% confidence interval [CI] 0.72 to 0.98) and a cross-validated AUC of 0.80 (95% CI 0.70 to 0.85). Sensitivity and specificity calculated using the Youden index were 0.79 and 0.84, respectively. Exhaled biomarker patterns were easy to obtain with the device and were able to differentiate children with uncontrolled symptomatic asthma from asymptomatic controls.

Characterization of Sicilian rosemary (Rosmarinus officinalis L.) germplasm through a multidisciplinary approach.

In Sicily, small differences exist between wild and cultivated rosemary biotypes; VOCs and genetic profiles may be a useful tool to distinguish them. A germplasm collection of Rosmarinus officinalis L. was harvested from 15 locations in Sicily. Eleven wild and four cultivated populations were collected and, due to the surveyed area covered, they can be considered as a representative panel of Sicilian genetic background of the species. Ex situ plant collection was transferred to the field cultivation in homogeneous conditions for characterizing through a multidisciplinary approach. The study included morphological traits observations (growth habitus, flower color, number and size of leaves, length and number of internodes), VOC profiles using HS-SPME, genome size by flow cytometry analysis, and genetic characterization by means of DNA and nuclear microsatellite (nSSR) investigation. To detect any pattern within- and among-populations variability, all morphological and chemical data were submitted to ANOVA, while clustering and structure population analysis were carried out using genetic profiles. The present work allowed us to distinguish rather well between wild and cultivated genotypes and to underline the biodiversity richness among rosemary Sicilian germplasm, never highlighted, useful for future breeding programs addressed to exploit this important resource.

The Pathophysiology of Bile Acid Diarrhoea: Differences in the Colonic Microbiome, Metabolome and Bile Acids

Background: Bile acid diarrhoea (BAD) is common, often unrecognised, or thought to be irritable bowel syndrome with diarrhoea (IBS-D). It results from increased loss of bile acids (BAs) into the colon but mechanisms are unclear. The gut microbiota plays key roles in the metabolism of primary BAs to form secondary BAs, which have differing impacts on intestinal metabolism and homeostasis. The aim of this study was to profile the gut microbiome in BAD and to investigate the differences in bacterial metabolic products and specific bile acids. Methods: Patients with BAD diagnosed by SeHCAT testing, were compared with other IBS-D patients, and healthy controls. Faecal 16S ribosomal RNA gene analysis was undertaken. Faecal short chain fatty acid (SCFA) and urinary fermentation metabolite profiles (volatile organic compounds; VOCs) were measured. BAs were quantified in serum and faeces. Findings: Faecal bacterial diversity was significantly reduced in patients with BAD, but several taxa were enriched compared to IBS-D. SCFA amounts differed in BAD, controls and IBS-D, with significantly more propionate in BAD. Separation of VOC profiles was evident between all groups with the greatest discrimination between IBS-D and controls. Unconjugated and primary BA in serum and faeces were significantly higher in BAD. The proportion of faecal primary BA was inversely related to SeHCAT values. Interpretation: BAD results in dysbiosis, with differences in metabolites including VOC, SCFA and higher concentrations of primary BAs when compared to IBS-D. These findings provide new mechanistic insights into the pathophysiology of BAD. Funding Statement: Funding was from UHCW Trust’s charity as well as the Midlands Gastroenterology Society and Bardhan Research and Education Trust (BRET). Declaration of Interests: JW has been a consultant for, and reports institutional grant funding from GE Healthcare, and Prometheus diagnostics. RA has delivered educational talks for GE Healthcare. No disclosures are made by all authors Ethics Approval Statement: Scientific and ethical approval was acquired from the local Research and Development Office as well as Warwickshire Ethical committee ref: 09/H1211/38. Written informed consent was obtained from all participants in the study.

Detection of Emerald Ash Borer Infestations in Living Green Ash by Noninvasive Electronic-Nose Analysis of Wood Volatiles.

The emerald ash borer (EAB) has been the most destructive and costly nonnative insect to threaten the health of ash (Fraxinus) species in North America for at least the past 25 years. The development of methods for detecting visually-hidden EAB galleries at early stages of infestation would provide a useful tool to more effectively facilitate the planning and implementation of targeted EAB pest-suppression and management activities. We tested the efficacy of using a dual-technology electronic-nose (e-nose)/gas chromatograph device as a means for detection of EAB infestations in green ash trees in different EAB-decline classes by analysis of VOC emissions in sapwood. We found significant differences in VOC profiles for trees from the four decline classes. The VOC composition, quantities, and types of volatile metabolites present in headspace volatiles varied considerably across sample types, and resulted in distinct e-nose smellprint patterns that were characteristic of each unique chemical composition. In addition, specific VOC metabolites were identified as potential healthy and EAB-infestation biomarkers, indicative of the health states of individual trees. Few significant differences in major bark phenolic compounds were found between ash decline classes using LC-MS. The e-nose was effective in discriminating between uninfested and EAB-infested trees based on sapwood VOC emissions.

Volatile Organic Compounds as Biomarkers of Gastrointestinal Diseases and Nutritional Status.

Purpose The purpose of this review was to identify the best solution for rapid and noninvasive diagnosis and long-term monitoring of patients affected by inflammatory gastrointestinal diseases, colon and gastric cancer, obesity in correlation to diet, and breast milk to evaluate exposure to VOCs in women and infants. Methods This review included 20 previously published eligible studies. VOC analysis has allowed us to highlight differences in lifestyles, intestinal microbiota, and metabolism. New innovative methods have been described that allow the detection and quantification of a broad spectrum of metabolites present in exhaled breath even at very low levels, some of which have been shown to be indicators of pathological conditions. Results Five studies were analyzed that involved VOC analysis in relation to type of diet. All of them showed that the type of diet can have an impact on metabolites excreted and therefore can be a useful tool in the nutritional studies related to metabolism and health and disease status. Two studies concerned VOC analysis in inflammatory bowel diseases, and the results showed that VOCs can distinguish active disease from remission; VOC profile is clearly different in patients. In particular, C15H30 1-pentadecene, 3-methyl-1-butanal, octane, acetic acid, alpha-pinene, and m-cymene are elevated in active ulcerative colitis. Four studies examined VOCs in gastric and colorectal tumors showing a change in metabolic biomarkers of cancer patients compared to the control group. Finally, the study of VOCs in breast milk has improved the understanding of the potential health risks of exposure of children to chemical pollutants. Conclusions VOC analysis allowed to highlight differences in behavior, lifestyle, and metabolism of individuals. Analytical methods are continuously developed to allow for better detection and quantification of metabolites, thus enabling the detection of a broader spectrum of pathophysiology and disease biomarkers.

Instrumental and Sensory Analysis for the Design of Complex Tropical Fruit Beverage Flavorings: the Case of Soursop

This study aimed at designing nature-identical flavorings for dairy drinks based on soursop (Anona muricata) VOCs profile, at different ripening stages, and after its processing into a fruit beverage, by combining conventional sensory analysis, and instrumental techniques: gas chromatography (GC/FID/MS) and a metal oxide (MOS)-based electronic nose. For this purpose, unripe fruits were harvested and ripened in controlled conditions while monitoring soluble solids, pH and acidity. Furthermore, ripe fruits were processed into a soursop sugary drink. Dichloromethane extracts of semi-ripe, ripe and overripe pulps, and ripe soursop drink, were analyzed by GC-FID/MS for assessing their VOCs profiles. In parallel, pulps at the same three ripeness degrees, and the soursop drink were analyzed by e-nose, in order to study changes in their aromatic profile. Fifty-two aroma compounds were identified. Terpenes were the most representative group of the semi-ripe stage, whereas esters were more predominant in the ripe and overripe pulps. A greater incidence of lactones and small-chain acids and alcohols in the latter, indicated the start of degradation. In the sugary drink, there was higher predominance of esters, whereas the relative concentration of terpenes and alcohols decreased, probably due volatilization during heat processing. E-nose showed a higher aromatic intensity in the ripe pulp, and principal component analysis (PCA) clearly differentiated the three ripening stages and the sugary soursop drink. Four nature-identical flavorings were developed according to the determined profiles. A descriptive-comparative sensory analysis of flavorings vs. their natural targets, using 13 flavor descriptors, allowed to adjust the formulations. The adjusted flavorings were added (0.08%) to a sweetened whole yogurt, and subjected to descriptive and consumer acceptance sensory tests. The perceived flavor of yogurts was successfully associated with the sensory profile of the fruits at their respective ripening/processing stage. Finally, the consumer test showed a better performance of overripe soursop-flavoring in terms of acceptance and approximation to a naturally-flavored drink, suggesting that consumers favor more complex creamy and cider notes of the overripe soursop.

VOC Emissions and Formation Mechanisms from Carbon Nanotube Composites during 3D Printing.

A commercially available, 3D printer nanocomposite filament of carbon nanotubes (CNTs) and acrylonitrile-butadiene-styrene (ABS) was analyzed with respect to its VOC emissions during simulated fused deposition modeling (FDM) and compared with a regular ABS filament. VOC emissions were quantified and characterized under a variety of conditions to simulate the thermal degradation that takes place during FDM. Increasing the residence time and temperature resulted in significant increases in VOC emissions, and the oxygen content of the reaction gas influenced the VOC profile. In agreement with other studies, the primary emitted VOC was styrene. Multiple compounds are reported in this work for the first time as having formed during FDM, including 4-vinylcyclohexene and 2-phenyl-2-propanol. Our results show that printing 222.0 g of filament is enough to surpass the reference concentration for inhalation exposure of 1 mg/m3 according to the EPA's Integrated Risk Information System (IRIS). The presence of CNTs in the filament influenced VOC yields and product ratios through three types of surface interactions: (1) adsorption of O2 on CNTs lowers the available O2 for oxidation of primary backbone cleavage intermediates, (2) adsorption of styrene and other VOCs to CNTs leads to surface-catalyzed degradation, and (3) CNTs act as a trap for certain VOCs and prevent them from entering vapor emissions. While the presence of CNTs in the filament lowered the total VOC emission under most experimental conditions, they increased the emission of the most hazardous VOCs, such as α-methylstyrene and benzaldehyde. The present study has identified an increased risk associated with the use of CNT nanocomposites in 3D printing.

In vitro profiling of volatile organic compounds released by Simpson-Golabi-Behmel syndrome adipocytes

Breath analysis offers a non-invasive and rapid diagnostic method for detecting various volatile organic compounds that could be indicators for different diseases, particularly metabolic disorders including type 2 diabetes mellitus. The development of type 2 diabetes mellitus is closely linked to metabolic dysfunction of adipose tissue and adipocytes. However, the VOC profile of human adipocytes has not yet been investigated. Gas chromatography with mass spectrometric detection and head-space needle trap extraction (two-bed Carbopack X/Carboxen 1000 needle traps) were applied to profile VOCs produced and metabolised by human Simpson Golabi Behmel Syndrome adipocytes. In total, sixteen compounds were identified to be related to the metabolism of the cells. Four sulphur compounds (carbon disulphide, dimethyl sulphide, ethyl methyl sulphide and dimethyl disulphide), three heterocyclic compounds (2-ethylfuran, 2-methyl-5-(methyl-thio)-furan, and 2-pentylfuran), two ketones (acetone and 2-pentanone), two hydrocarbons (isoprene and n-heptane) and one ester (ethyl acetate) were produced, and four aldehydes (2-methyl-propanal, butanal, pentanal and hexanal) were found to be consumed by the cells of interest. This study presents the first profile of VOCs formed by human adipocytes, which may reflect the activity of the adipose tissue enzymes and provide evidence of their active role in metabolic regulation. Our data also suggest that a previously reported increase of isoprene and sulphur compounds in diabetic patients may be explained by their production by adipocytes. Moreover, the unique features of this profile, including a high emission of dimethyl sulphide and the production of furan-containing VOCs, increase our knowledge about metabolism in adipose tissue and provide diagnostic potential for future applications.

Effects of humidity, CO2 and O2 on real-time quantitation of breath biomarkers by means of PTR-ToF-MS

Proton transfer reaction time-of-flight mass spectrometry (PTR-ToF-MS) represents an attractive tool for the real-time analysis of VOC profiles in human breath. Quantification of breath VOCs by means of direct MS may be affected by the matrix, as human breath not only contains several hundred VOCs at the ppbV–pptV level, but is water saturated and contains percentage levels of CO2. Investigation of breath biomarkers in clinical studies requires quantitative and comparable results. We therefore systematically assessed the effect of humidity, CO2 and O2 on the results of PTR-MS analysis. We investigated more than 20 VOCs, including aldehydes, ketones, aromatic compounds and hydrocarbons with different sample humidity, CO2 and O2 content. The influence of data processing (e.g. normalization to the H3O+ ion count) was also addressed. An increase of the H3O+ count of about 20% was observed when the humidity in the sample was increased to breath levels. Large differences regarding the measured VOC intensities were found between the dry and humid samples. Data normalization to the H3O+ or water-clusters could not fully compensate for the humidity-dependent effects. However, as the determination of most VOCs linearly depends on the humidity over the whole investigated range, factor-based correction seems possible. The effects of CO2 were more pronounced in the dry samples than in the humid samples but only had a minor influence on the results. The same was true for the influence of O2. For the reliable quantification of VOCs in clinical studies and for the standardization of VOC research, well-adapted calibration standards are required for PTR-MS analysis.

The effect of biosilver nanoparticles on different bacterial strains’ metabolism reflected in their VOCs profiles

The use of silver nanoparticles has become in recent years a growing interest for many researchers, due to their bacteriostatic and bactericidal properties and synergetic effects when they are used together with antibiotics, for an increased efficiency and less adverse reactions in the treatment of bacterial infections. Gas chromatography coupled with mass spectrometry (GC-MS), which is considered ‘the golden standard’ in chemical analysis, has proven to be a reliable instrument, perfectly suitable for clinical analysis. In this work, three bacterial strains, Escherichia coli (E. coli), Klebsiella oxytoca (K. oxytoca) and Staphylococcus saccharolyticus (S. saccharolyticus) were treated with biosilver nanoparticles (bioAgNPs). Headspace and GC-MS analysis was used for the detection of volatile metabolites. We observed decreased amounts of alcohols and carbonyl components (mainly ketones) in K. oxytoca and S. saccharolyticus bacteria incubated with silver. In contrast, biosilver nanoparticles added to E. coli increased the amount of VOCs, mainly hydrocarbons and alcohols. Our results have successfully demonstrated that the treatment of bacterial strains with bioAgNPs has a direct influence on their VOC profiles, by modifying the number of metabolic markers. Connected with this, the inhibition of bacteria is supposed, and consequently both the bacteriostatic and/or bactericidal effects of bioAgNPs on all three bacterial strains investigated were revealed.