VOC analysis for rapid, early detection of bacteria, mold, and mycoplasma in cell and tissue cultures.

Breath analysis for healthcare and disease monitoring has become popular recently in global. There are hundreds of volatile organic compounds (VOCs) exist in human breath, and some of them can offer medical and biological information as the bloodstream. Particularly,acetone is one of the typical VOCs in exhaled breath, which is related to lipid metabolism in fasting, exercise and diabetes mellitus. The breath acetone concentrations have been previously shown to correlate strongly with blood acetone concentrations as well as with other ketones such as beta-hydroxybutyrate. Besides, there are many studies found the correlation between the breath acetone concentrations and blood glucose concentrations. Previous research indicated that the breath acetone concentration in healthy people shows the range from 200 to 900 ppb and higher concentration was found in breath of diabetic patients. Increase of the acetone concentration is usually a sign that cells cannot effectively use glucose as energy source, which often occurs in starvation, aerobic exercise, lack of insulin or resistance of insulin. Thus, acetone in exhaled breath has a potential to be a biomarker for non-invasive monitoring the progressive of diabetes. Typical quantitation of gaseous acetone usually uses gas chromatography with mass spectrometry (GC/MS) or proton transfer reaction mass spectrometry (PTR-MS). These methods are highly sensitivity but still have disadvantages in cost, measurement time and hard for continuity. Therefore, a rapid, convenient and highly selective method for acetone determination is strongly required. In this study, a highly sensitive acetone bio-sniffer (gas-phase biosensor) was developed and used to assess the acetone from exhale breath for evaluating the lipid metabolism. Nicotinamide adenine dinucleotide (NADH)-dependent secondary alcohol dehydrogenase (S-ADH) is a kind of enzyme that can reduce acetone to be isopropanol and meanwhile oxidase NADH to be NAD+ in acidic condition. It is known that NADH can be excited by UV (ultraviolet) light at central wavelength of 340 nm and release a fluorescent emission at peak of 490 nm simultaneously, while NAD+ do not have similar optical property. Thus, acetone concentration can be measured using the decreasing of NADH fluorescence intensity that is consumed by the enzymatic reaction of S-ADH. The fluorometric acetone bio-sniffer was composed of a NADH fluorescence measurement system, a flow-cell attaching on the fiber probe and an enzyme-immobilized membrane. The NADH measurement system consisted of a UV-LED as the excitation light source, band-pass filters ( λ = 340 ± 10 nm and λ = 490 ± 10 nm) for reducing noise, a photomultiplier tube (PMT) as fluorescence detector and bifurcated optical fibers for assemble. S-ADH was immobilized on the hydrophilic-PTFE membrane and equipped on the top of flow-cell by silicone O-ring. Phosphate buffer, which contained NADH, was circulated in the flow-cell to supply fresh co-enzyme and eliminate isopropanol and NAD+that produced by the enzyme membrane. When bio-sniffer contacted the gaseous acetone, enzymatic reaction that mentioned above occurred immediately and the change of fluorescence would detect by the PMT. This acetone bio-sniffer showed rapid reaction, highly sensitivity and selectivity. When the acetone vapors were supplied to the sensing region, fluorescent intensity decreased immediately and reached to a steady state. Then, the intensity would return to the initial value in short time when the acetone vapor supply was stopped. The relation between the concentration of acetone and the change of fluorescent intensity was investigated and the dynamic range was confirmed from 20 to 5300 ppb of acetone in the gas phase. This range encompasses the concentration of acetone vapors found in breath of healthy people and of those suffering from disorders of carbohydrate metabolism. The selectivity of the S-ADH was also characterized; several different VOCs were employed to compare the responses. The interference of 2-butanol and 2-pentanone were ignorable because they contained in healthy people in very low concentration. Finally, we applied the bio-sniffer to measure breath acetone for evaluation of lipid metabolism during long time fasting and an aerobic exercise test. The results showed that the mean breath acetone concentration of long time fasting healthy volunteers were higher than those who did not have fasting and display significant difference. Furthermore, the concentration of acetone in breath was observed significantly increase during aerobic exercise and it would recover to the initial value after long time rest. This highly sensitivity acetone bio-sniffer provides a new kind of analytical tool for non-invasive evaluation of human lipid metabolism and it is also expected to use for the clinical applications such as monitoring the progression of diabetes mellitus and diagnosis of other metabolism diseases.

Differential response of porcine osteoblasts and chondrocytes in cell or tissue culture after 5-aminolevulinic acid-based photodynamic therapy

The Mediterranean fruit fly (Medfly) Ceratitis Capitata (Diptera: Tephidae), as most of the Tephritidae species, is a pest of great economic importance around the world. For Integrated Pest Management (IPM) and biological pest management purposes, this research will investigate characterization of the broadest possible range of volatile organic compounds and the possible changing trends of volatile biological emissions during development stages of insect. During the last years, many types of research have been done to understand chemical communications between pest-pest interactions and about the insect responses to specific volatile organic compounds. An early comparison of the VOCs emitted from larvae, pupae and adult was performed. Our research focuses on the comparison of volatile compounds emitted from a different stage of Medfly using stable isotope 13C6-glucose. Gas Chromatography (GC) technique coupled with Flame Ionization Detection (FID) and gas chromatography with mass spectrometry (GC-MS) for identification of VOCs was employed. Head Space-Solid Phase Micro Extraction HSSPME method with Three-phase fiber 50/30 µm divinylbenzene/carboxen/ polydimethylsiloxane (DVB/CAR/PDMS) was used. The results showed that there are different chemicals emitted in a different stage of Medfly (Larvae, pupae, and adults M/F) especially in the adult stage. GC-MS detected 27 compounds from larvae, 23 compounds from pupae and 29 compounds from adults. These different VOCs emitted in different stages of Medfly were clearly displayed, and a broad range of emitted volatile compounds was successfully described. The characterization of release patterns could be useful tool for the selection of compounds and for further investigated in biological studies to understand of the key semi-chemicals involved in medfly behaviour.

In der vorliegenden Arbeit wurden zwei Modifikationsverfahren an Eichenholz untersucht. Einerseits wurde Eiche einer Hitze‐Druck‐Dämpfung (engl. heat‐pressure steamed HPS) im Autoklaven unterzogen (Druck < 2 bar, Temperatur 120–140 °C), andererseits wurde industriell (mit Ammoniak) gedämpfte Eiche analysiert (bekannt unter dem Begriff Räuchereiche). Im Rahmen der Untersuchung wurden die Farbänderung infolge des Verfahrens und die Farbstabilität in Abhängigkeit der Bewitterungsart und ‐zeit bewertet. Die Proben wurden weiter hinsichtlich ihres Emissionsverhaltens untersucht. Die VOC‐Emissionen (flüchtige organische Verbindung) wurden nach DIN ISO 16000 in der Emissionsprüfkammer bestimmt. Die Auswertung der VOC‐Messung erfolgte mittels Gaschromatographie und Massenspektroskopie, die Bestimmung der Aldehyde erfolgte durch Flüssigchromatographie und UV‐Detektion.Die Hitze‐Druck‐Dämpfung führt zu einer deutlichen Farbänderung und ist hinsichtlich ihrer Erscheinung der Behandlung mit Ammoniak sehr ähnlich, weshalb sich dieses Produkt als Alternative für die traditionelle Räucherung anbietet. Im Verlauf der künstlichen und natürlichen Bewitterung kommt es zu einer Aufhellung der Produkte, im Vergleich dazu dunkeln unbehandelte Referenzprodukten deutlich nach.Die Hitze‐Druck‐gedämpfte Eiche (HPS‐Eiche) und die mit Ammoniak behandelte Eiche zeigen in Bezug auf die totale VOC‐Emission ein ähnliches Verhalten. Bei der Betrachtung der Einzelemissionen ergeben sich jedoch deutliche Unterschiede. Die HPS‐Eiche emittiert hauptsächlich Furfural (186 µg/m3 nach 28 Tagen). Bei mit Ammoniak gedämpfter Eiche wird in erster Linie Acetamid emittiert (159 µg/m3 nach 28 Tagen). Die Formaldehydemission für beide Produkte ist niedriger als 5 µg/m3. Es wird kein Formaldehyd während der beiden Prozesse gebildet.Influence of heat pressure steaming (HPS) on the optical appearance and the emission behaviour of oak wood. In this work we investigated oak, which was thermal treated using two different, but common procedures: On the one hand, the oak wood was heat‐pressure steamed (HPS) in an autoclave (< 2 bar and 120–140 °C), on the other hand, the oak wood was fumigated with ammoniac at room temperature. The process at high pressure and temperature can be more environmental friendly as the fumigated wood as only water is needed.The heat‐pressure steamed oak wood was investigated regarding the influence of the treatment method on the color after treatment and the color stability after artificial and outdoor weathering. The second parameter of concern was the material emissions of treated oak wood. The VOC emissions (volatile organic compounds) were measured according to DIN ISO 16000, which includes the sample preparation, the emission chambers and the measurement of VOC by gas chromatography with mass spectrometry (GC‐MS) and the aldehydes by liquid chromatography and UV‐detection (HPLC‐UV).Heat‐pressure steamed oak and ammoniac steamed oak do not differ significantly in the total VOC emissions. However if the two procedures are compared by single components, a clear difference is visible: The main single component of heat‐pressure steamed oak is furfural with a concentration of 186 µg/m3 after 28 days in the emission chamber. The most important emission of a single compound in the ammoniac steamed wood is acetamine with a concentration of 159 µg/m3 after 28 days. The formaldehyde concentrations of both wood treating procedures are lower than 5 µg/m3. During the modification treatments no formaldehyde is produced.

Application of an electronic nose with novel method for generation of smellprints for testing the suitability for consumption of wheat bread during 4-day storage

The study of protein synthesis in farm animals is uncommon despite its potential to increase knowledge about metabolism and discover new biomarkers of health and growth status. The present study describes a novel dynamic proteomics approach for the measurement of protein fractional synthesis rate (FSR) in broiler chickens. Chickens received a 10g/kg oral dose of 2 H2 O at day 21 of their life. Body water 2 H abundance was measured in plasma samples using a portable Fourier transform infrared spectrometer. Free and protein-bound amino acids (AAs) were isolated and had their 2 H enrichment measured by gas chromatography with mass spectrometry (GC/MS). Peptide 2 H enrichment was measured by proteomics analysis of plasma and muscle samples. Albumin, fibrinogen and muscle protein FSR were calculated from GC/MS and proteomics data. Ala appeared to be more enriched at the site of protein synthesis than in the AA free pools. Glu was found to be the AA closest to isotopic equilibrium between the different AA pools. Glu was used as an anchor to calculate n(AA) values necessary for chicken protein FSR calculation in dynamic proteomics studies. FSR values calculated using proteomics data and GC/MS data showed good agreement as evidenced by a Bland-Altman residual plot. A new dynamic proteomics approach for the measurement of broiler chicken individual protein FSR based on the administration of a single 2 H2 O oral bolus has been developed and validated. The proposed approach could facilitate new immunological and nutritional studies on free-living animals.

Accurate and reproducible quantification of volatile organic compounds (VOCs) is essential in environmental monitoring, clinical diagnostics, and quality control. Thermal desorption gas chromatography (TD-GC) is widely used for VOC analysis, often coupled with mass spectrometry (MS) for reliable identification. Ion mobility spectrometry (IMS) has gained attention for its high sensitivity and rapid detection. While GC-IMS and GC-MS are well established, TD-GC coupled to both IMS and MS has not been systematically investigated. This study presents a comprehensive assessment of a TD-GC-MS-IMS system, combining the strengths of both detectors. A mobile flow- and temperature-controlled sampling unit for TD tubes was developed for standardized applications, designed to introduce both gaseous and liquid samples. The long-term stability of TD-GC-IMS was assessed over 16 months with 156 measurement days using ketones. Relative standard deviations for signal intensities ranged from 3% to 13%, retention time deviations from 0.10% to 0.22%, and drift time deviations from 0.49% to 0.51%. Comparative evaluation showed IMS was approximately ten times more sensitive than MS, achieving limits of detections in the picogram/tube range. In contrast, MS exhibited a broader linear range, maintaining linearity over three orders of magnitude (up to 1000 ng/tube), while IMS retained linearity for one order of magnitude (e.g., 0.1 to 1 ng/tube for pentanal) before transitioning into a logarithmic response. To improve IMS quantification, a linearization strategy extended the calibration range from one to two orders of magnitude. These findings establish a standardized TD-GC-MS-IMS framework, improving reproducibility and comparability for clinical, environmental, and industrial VOC analysis.Supplementary InformationThe online version contains supplementary material available at 10.1007/s00216-025-05933-w.

Volatile organic compounds (VOCs) for the non-invasive detection of pancreatic cancer from urine

Application of solid-phase microextraction for the determination of organophosphorus pesticides in textiles by gas chromatography with mass spectrometry

IntroductionOrganism-level microbial identification is a well-established topic in literature. Due to biosafety concerns, specifically identifying pathogenic bacteria is of critical importance. This study positions Deep Learning (DL) - based chemometric analysis as a promising strategy for organism-level microbial identification, with potential translational value for rapid diagnostics. Various chemometric methods have been applied to analyze pure and mixed cultures of microorganisms and generate data via Volatile Organic Compounds (VOCs) fingerprints for classification. Although Gas Chromatography - Ion Mobility Spectrometry (GC-IMS) is a promising chemometric technique in this field, limited research has explored its potential for organism-level microbial identification. Materials and methodsIn this study, GC-IMS prototypes were employed to generate two-dimensional spectral data, which were then used to train supervised classification models. Utilizing a publicly available dataset of four microorganisms, we conduct a series of experiments to perform multi-class classification of pure and mixed cultures. Additionally, we introduce innovative experiments for distinguishing bacteria from fungi and Gram-positive from Gram-negative bacteria. We further investigate the presence and pureness of two pathogenic bacteria, Escherichia coli and Pseudomonas fluorescens, within the cultures. To achieve this, we apply eight Machine Learning and DL baseline methods, while following a five-fold cross-validation evaluation protocol and presenting a wide set of evaluation metrics to ensure result reproducibility and models’ generalization. A further evaluation of DL models is also conducted to report the training times and the number of parameters of the proposed DL methods.ResultsOur key findings highlight a Fully Connected Neural Network (FCNN) with four hidden layers as the most efficient model, consistently achieving the best performance across all tasks in comparison to the other tested models of this study. Additionally, the FCNN model provides fast training and maintains a relatively small number of parameters compared to other DL approaches. DiscussionWhile the dataset’s limited size and class imbalance present challenges such as potential overfitting and optimistic bias, the results achieved so far are encouraging and demonstrate the model’s strong potential. Future work should aim to expand the dataset across multiple sites and instruments and include clinical validation on real-world samples to further enhance generalizability and ensure translational impact.

BackgroundChanges in exhaled volatile organic compounds (VOCs) can be used to discriminate between respiratory diseases, and increased concentrations of hydrocarbons are commonly linked to oxidative stress. However, the VOCs identified are inconsistent between studies, and translational studies are lacking.MethodsIn this bench to bedside study, we captured VOCs in the headspace of A549 epithelial cells after exposure to hydrogen peroxide (H2O2), to induce oxidative stress, using high-capacity polydimethylsiloxane sorbent fibres. Exposed and unexposed cells were compared using targeted and untargeted analysis. Breath samples of invasively ventilated intensive care unit patients (n=489) were collected on sorbent tubes and associated with the inspiratory oxygen fraction (FIO2) to reflect pulmonary oxidative stress. Headspace samples and breath samples were analysed using gas chromatography and mass spectrometry.ResultsIn the cell, headspace octane concentration was decreased after oxidative stress (p=0.0013), while the other VOCs were not affected. 2-ethyl-1-hexanol showed an increased concentration in the headspace of cells undergoing oxidative stress in untargeted analysis (p=0.00014). None of the VOCs that were linked to oxidative stress showed a significant correlation with FIO2 (Rs range: −0.015 to −0.065) or discriminated between patients with FIO2 ≥0.6 or below (area under the curve range: 0.48 to 0.55).ConclusionDespite a comprehensive translational approach, validation of known and novel volatile biomarkers of oxidative stress was not possible in patients at risk of pulmonary oxidative injury. The inconsistencies observed highlight the difficulties faced in VOC biomarker validation, and that caution is warranted in the interpretation of the pathophysiological origin of discovered exhaled breath biomarkers.

More than 170 polyunsaturated tocopherol-related compounds in a vitamin E capsule: Countercurrent chromatographic enrichment, gas chromatography/mass spectrometry analysis and preliminary identification of the potential artefacts

The article is devoted to the chromatographic analysis of fingerprints and the metabolomic screening of compounds in the rhizomes of Gynostemma pentaphyllum (Thunb.)Makino.The object of study was the fresh and dried rhizomes of Gynostemma pentaphyllum (Thunb.)Makino, grown on the territory of the Republic of Bashkortostan (GPS coordinates of the collection of raw materials: 54.79435 north latitude, 55.85707 east longitude).The fingerprints of flavonoids and saponins were analyzed by thin-layer and high-efficiency thin-layer chromatography (TLC, HETLC).Metabolomic screening of G. pentaphyllum rhizomes was performed by gas chromatography with mass spectrometry (GC/MS).According to the TLC and HETLC data, substances of a flavonoid nature were found -rutin (Rf=0.480.02),quercetin (Rf=0.890.02)and triterpene --escin (Rf=0.460.02).GC/MS has a component composition consisting of hydrocarbons (cyclic, acyclic, dicarboxylic acids, their derivatives), terpenoids (monoterpenes, sesquiterpenes, diterpenes, their derivatives and from the group of aromatic compounds), flavonoids, derivatives of alkyl carboxylic acids, heterocyclic and steroidal compounds.The component composition of the recognized substances of G. pentaphyllum rhizomes may cause cytotoxic, antibacterial, adaptogenic and other effects that require further detailed preclinical and clinical studies.

Identification and quantification of seven fused aromatic rings C26H14peri-condensed benzenoid polycyclic aromatic hydrocarbons in a complex mixture of polycyclic aromatic hydrocarbons from coal tar

Isolation of two Δ5 polymethylene interrupted fatty acids from Podocarpus falcatus by countercurrent chromatography