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The quantitative and qualitative composition of volatile organic compounds (VOCs) of human exhaled air, the air environment of various types of entomopathogenic fungi (EPF) of the genus Lecanicillium, used as an alternative to chemical pesticides to protect plants from pests, cabbage moth caterpillars, as well as spined soldier bug from the shield family, was studied using a quadrupole mass spectrometer. The main components found were acetone, acetic acid, and isoprene. These components in human exhalation are significant indicators for non-invasive disease diagnosis. For the first time, sulfur dioxide was found in the composition of VOC EPF, as one of the possible repellents. The caterpillars of cabbage moth secrete exclusively acetic acid. [ABSTRACT FROM AUTHOR]

The role of hydrogen peroxide molecule (Н2О2) in the vital functions of biological objects has been considered. The mechanisms of Н2О2 formation and its relationship with redox reactions, as well as some possible methods of analyzing the Н2О2 content in liquid and gaseous media, are discussed. In particular, the possibility of using highly sensitive methods of laser spectral analysis for detecting Н2О2 traces in exhaled air, which are promising for diagnostics of various pathologies, is considered. The absorption spectra of exhaled air are analyzed, and the strongest H2O2 spectral lines (isolated from the influence of other gaseous metabolites), applicable for detecting Н2О2 by diode laser spectroscopy, are chosen. [ABSTRACT FROM AUTHOR]

Fine and nanosize particles of both natural and anthropogenic origin can be present in the atmospheric air and affect the environment and human health. The effect of cobalt ferrite (CoFe2O4), magnetite (Fe3O4), and tin dioxide (SnO2) nanopowder inhalation of laboratory animals on the carbon dioxide content in air samples taken from the noses of these animals is studied. The CO2 concentration is determined from the absorption spectra of air samples recorded with a laser photoacoustic (PA) gas analyzer. It is ascertained that inhalation of magnetite nanoparticles leads to a decrease in the concentration of carbon dioxide in the samples of exhaled air of laboratory animals, which can indicate a negative effect of this exposure. [ABSTRACT FROM AUTHOR]

Background: Infection with SARS-CoV-2 causes corona virus disease (COVID-19). The most standard diagnostic method is reverse transcription-polymerase chain reaction (RT-PCR) on a nasopharyngeal and/or an oropharyngeal swab. The high occurrence of false-negative results due to the non-presence of SARS-CoV-2 in the oropharyngeal environment renders this sampling method not ideal. Therefore, a new sampling device is desirable. This proof-of-principle study investigated the possibility to train machine-learning classifiers with an electronic nose (Aeonose) to differentiate between COVID-19-positive and negative persons based on volatile organic compounds (VOCs) analysis. Methods: Between April and June 2020, participants were invited for breath analysis when a swab for RT-PCR was collected. If the RT-PCR resulted negative, the presence of SARS-CoV-2-specific antibodies was checked to confirm the negative result. All participants breathed through the Aeonose for five minutes. This device contains metal-oxide sensors that change in conductivity upon reaction with VOCs in exhaled breath. These conductivity changes are input data for machine learning and used for pattern recognition. The result is a value between − 1 and + 1, indicating the infection probability. Results: 219 participants were included, 57 of which COVID-19 positive. A sensitivity of 0.86 and a negative predictive value (NPV) of 0.92 were found. Adding clinical variables to machine-learning classifier via multivariate logistic regression analysis, the NPV improved to 0.96. Conclusions: The Aeonose can distinguish COVID-19 positive from negative participants based on VOC patterns in exhaled breath with a high NPV. The Aeonose might be a promising, non-invasive, and low-cost triage tool for excluding SARS-CoV-2 infection in patients elected for surgery. [ABSTRACT FROM AUTHOR]

In clinical practice, exhaled air analysis is a promising approach for diagnosing lung cancer due to a possibility of rapid and noninvasive sampling. We analyzed the exhaled air of 80 patients with lung cancer to identify differences in the profiles of volatile organic compounds in patients with different histological types and localization of cancer using gas chromatography–mass spectrometry. Some volatile organic compounds and their ratios have been identified, statistically signficant differences in concentrations of which have been found in samples with different localization and histological type. [ABSTRACT FROM AUTHOR]

An experimental setup and a method for analyzing multicomponent gas mixtures, including human-exhaled air, have been presented. The installation consists of a quantum cascade laser that is tunable in the wavelength range of 5.3–12.8 µm and has a peak power of 150 mW and a multi-pass Herriot gas cell that allows obtaining an optical path of up to 76 m. The registration time of a single spectrum is about 50 ms. For acetone and ethanol which are potential biomarkers of some human diseases the sensitivity threshold at the sub-ppm level has been experimentally determined. A system of sample preparation and pre-drying that allows analyzing both multicomponent gas mixtures and the air exhaled by a person has been proposed. The variants of application of the described installation in biomedical applications has been proposed. [ABSTRACT FROM AUTHOR]

Methods of diode laser spectroscopy were applied for monitoring of fast physiological variations in the content of endogenous carbon monoxide (CO) in exhaled air. To this end, a CO analyzer based on a tunable diode laser emitting radiation around 2.35 μm at room temperature was constructed. CO concentration in exhaled air was determined by measuring resonance absorption of CO molecule at the R(6) line of the 0–2 band in the vicinity of 4285 cm–1. Using this line that is well separated from the nearby absorption lines of Н2О enables high selectivity of CO analysis under the conditions of high humidity of analyzed air. The possibility of monitoring fast physiological variations of CO content in exhaled air of humans and animals by means of the developed system was demonstrated in studies involving a number of physiological load tests, such as breathing pure oxygen (both humans and rats), physical load, and hyperventilation. The dynamics of CO release caused by certain pharmaceutical drugs was also studied. It is demonstrated that laser diagnostics of CO in the spectral region near 2.35 μm allows detecting fast dynamic processes of release of this gas molecule that represents one of the signaling and metabolite molecules in exhaled air when conducting various physiological and medical studies, investigating trends and interrelation of processes responsible for production, transport, buffering, and release of CO in an organism. [ABSTRACT FROM AUTHOR]

Currently, patients with stomach and duodenum diseases should be examined using diagnostic tests for Helicobacter pylori infection. Diagnostic methods available in the arsenal of clinicians make it possible to identify Helicobacter pylori in almost 100% of cases. A competent approach to the selection of a diagnostic test provides high-quality, timely, and economical verification of the pathogen. The paper provides information on the currently available diagnostic procedures for the detection of Helicobacter pylori infection and the results of the diagnosis of helicobacteriosis based on the activity of urease in saliva. The main area of research is the development of an analytical method based on the quantitative determination of ammonia and the detection of amines and aliphatic acids in exhaled air using signals from an array of diverse piezoelectric chemical sensors. Simple data processing algorithms were applied, and qualitative and quantitative decision-making criteria were substantiated. The method of analysis using chemical sensors is characterized by high specificity (96% for ammonia) and sensitivity (90%); it does not require special sample preparation and is indispensable in large-scale studies and personal monitoring and for choosing treatment tactics. [ABSTRACT FROM AUTHOR]

We optimized procedures for the collection, preparation, and storage of samples of exhaled air and the conditions for determining volatile organic compounds in exhaled air by gas chromatography–mass spectrometry (GC–MS), the presence or change in the concentration of which can be caused by lung cancer. The analysis circuit includes group adsorption preconcentration followed by the thermal desorption and determination of analytes by GC–MS. Polymer bags of a Tedlar® film were used for sample collection. The conditions and periods of the storage of samples in bags and adsorption tubes are determined. A method for cleaning and conditioning bags is proposed. For preconcentrating exhaled air components, we used hydrophobic adsorbents (Porapak™ P, Porapak™ Q, and Tenax® TA) and three-section tubes containing Tenax® GR, Carbopack™ B, and Carbosieve® S-III. Their relative efficiency was evaluated by assessing the residual background of gas emission from the adsorbent, the magnitude of the analytical signal, the efficiency of adsorption/desorption, and the efficiency of storage. The conditions for the preconcentration of volatile organic compounds (volume and rate of aspiration, time, and temperature of thermal desorption) are optimized. The main volatile organic compounds in the exhaled air of conditionally healthy volunteers were identified, and their concentrations are evaluated. [ABSTRACT FROM AUTHOR]

Acrolein is a pollutant released daily to the indoor environment from different sources. The present study reports the development of a simple and sensitive cold fiber solid phase microextraction sampling method for the determination of acrolein in exhaled air and indoor air by gas chromatography mass spectrometry. O-(2,3,4,5,6-pentafluorobenzyl) hydroxylamine was used as derivatizing agent supported on a 65-μm polydimethylsiloxane-divinylbenzene SPME fiber. An acrolein permeation tube at 326.25 ng min rate was used to generate gaseous standards. The method shows good results for main validation parameters. The limits of detection and quantification were 2.88 and 5.08 μg m, respectively, for indoor analysis; and 2.40 and 3.79 μg m, respectively, for exhaled air analysis. The precision showed standard deviation ranges from 6.00 to 8.00% for intra-assay analyses and from 8.00 to 10.00% for inter-assay analyses. After optimizing the conditions, analyses of real samples were performed on indoor environments contaminated by cigarette smoke, or heated oil, including pastry shops, restaurants, churros stands, and closed parking cars located in the city of Belo Horizonte, Brazil. Acrolein breaths of exposed people were also determined. A good Pearson correlation coefficient ( r = 0.901) was observed between the concentration of acrolein in indoor air and exhaled air, allowing to propose acrolein breath as environmental exposure biomarker. [ABSTRACT FROM AUTHOR]

Accurate diagnosis of different bronchopulmonary diseases is important in clinical practice. This study involved 20 healthy volunteers and 77 patients with bronchopulmonary diseases, including chronic obstructive pulmonary disease (COPD), bronchial asthma, pulmonary tuberculosis, and community-acquired pneumonia. The absorption spectrum of exhaled air samples was recorded on an intra-cavity photo-acoustic gas analyzer (ILPA-1, Special Technologies, Ltd., Russia) with photo-acoustic detectors and CO laser with a tuning range from 9.2 to 10.8 μm. In conclusion, analysis of the Mahalanobis distance-based absorption spectral profiles of breath air from bronchopulmonary patients and healthy volunteers allows the formulation of a preliminary diagnosis. [ABSTRACT FROM AUTHOR]

The effect of metabolic syndrome risk factors on the content of light hydrocarbons (C-C) in exhaled air has been studied with the participation of students of Novosibirsk State Medical University. Gas chromatography was performed in an EKHO-EW-FID chromatograph with a short multichannel column. The study revealed sex-related differences between the concentrations of light hydrocarbons in exhaled air. In addition, some factors, such as smoking and type 2 diabetes mellitus in relatives, affect the content of C-C compounds in exhaled air of women only. However, overweight is correlated with the content of acetone (C) in exhaled air only in men. Thus, the metabolic changes caused by the presence of age-specific metabolic syndrome risk factors lead to the changes in the gas composition of exhaled air and can be detected and used for early diagnosis. [ABSTRACT FROM AUTHOR]

Airway irritation involves a variety of reflex mechanisms. Tracheal and bronchial C fibres and rapidly adapting fibres mediate cough, bronchoconstriction, and mucosal vasodilation. Workplace respiratory irritants can have a variety of effects in relation to asthma. Very high exposures can cause new-onset asthma, clinically presenting as reactive airways dysfunction syndrome or irritant-induced asthma. Symptoms after exposure to irritants depend on aggregate characteristics, water solubility and dose. Measurement of pulmonary function in response to irritants includes baseline spirometry, monitoring of across-shift changes and changes in non-specific bronchial responsiveness as well as bronchial responsiveness to inhaled allergens. Following irritant exposure, inflammatory changes within the airways are monitored by bronchoalveolar lavage or – less invasively – by sputum markers. A completely non-invasive approach not limited in repeatability is the investigation of inflammatory markers in exhaled air. However, the diagnostic and prognostic values of these novel markers have still to be demonstrated. [ABSTRACT FROM AUTHOR]

Exhaled air was analyzed for tetrachloroethene (PER) in teachers and 4-5-year-old pupils of a kindergarten situated near a factory, and in residents of an old folks' home situated near a former chemical waste dump. The PER concentrations were higher in the exhaled air of children living near the factory (mean 24 μg/m, n=6) than in control children (mean 2.8 μg/m, n=11). In the old folks' home, the PER concentrations in the exhaled air of people living on the first floor were higher (mean 7.8 μg/m, n=10) than in the exhaled air of the people living on the second floor and higher (mean 1.8 μg/m, n=19). From the results of this study, it is clear that in environmental exposure to tetrachloroethene, biological monitoring of exhaled air is a simple, efficient, effective and convenient method of assessing total ambient exposure of both young and aged subjects. [ABSTRACT FROM AUTHOR]

A gas chromatographic method for simultaneous determination of trichloroethylene (TRI), trichloroethanol (TCE) and trichloroacetic acid (TCA) in blood and TRI, TCE in exhaled air is described. The determination in blood is based on the relative volatility of TRI, TCE and TCA methylester, which offers the possibility of headspace analysis. The gaschromatograph is equipped with an electron capture detector. Exhaled air, collected during 1 min normal breathing is analysed for TRI and TCE under the same gas chromatographic conditions as the headspace vapour of blood. After exposure of 4 volunteers to 70 and 140 ppm TRI a close relation over a wide range between the concentrations TRI and TCE in blood and in exhaled air is obtained. The TRI resp. TCE concentration in blood is about 23 resp. 15.000 times higher than in exhaled air. [ABSTRACT FROM AUTHOR]

An experiment was designed to determine whether the respiratory retention of sytrene vapor, as estimated from measurements of end-exhaled air, was the same during periods of both constant and fluctuating exposure. Six human subjects were exposed to styrene inside an experimental chamber. A computer-controlled system was used to generate time-varying air concentrations of styrene over 4-5 h in both multistep sequences of constant exposure (four subjects exposed to 15-99 ppm. of styrene in 100-min steps) and fluctuating patterns representative of occupational exposures (two subjects exposed to mean concentrations of styrene of 50 ppm). In the latter case, lognormally distributed exposures, which fit one of two first-order autoregressive models, were generated at intervals of 2.5 min. It was found that the concentration of styrene in end-exhaled air was reduced by about half if the subject inhaled one to three breaths of clean air prior to sampling. This suggests that significant amounts of styrene were desorbed from the lining of the lungs during the initial exhalation. The retention of styrene vapor during constant exposures was 0.935 and was independent of the level. During each of the two sets of fluctuating exposure the retention of sytrene was also constant and was independent of both the variance and the autocorrelation coefficient. However, the retention of styrene during fluctuating exposure (estimates ranged from 0.957 to 0.973) was significantly higher than that observed during the constant exposures. It is speculated that the difference in retention between the constant and the fluctuating exposure regimens is related to non-steady-state behavior of styrene in the richly perfused tissues, as suggested by Opdam and Smolders (1986) regarding tetrachloroethylene exposure. [ABSTRACT FROM AUTHOR]

To compare two methods of biological monitoring for the evaluation of risk of occupational exposure to n-hexane, we analyzed the relationship between environmental exposure to this solvent and urinary excretion of 2,5-hexanedione and n-hexane in exhaled air in 69 workers employed in the shoe industry. Environmental exposure to the solvent was monitored with personal diffusive samplers, which were desorbed with carbon sulfide and analyzed by gas chromatography. To measure 2,5-hexanedione, urine was subjected to acid hydrolysis, separation in octadecyl silane columns, elution with 5% aqueous acetonitrile solution and extraction with dichloromethane, followed by gas chromatography. In exhaled air, n-hexane was measured with a sampling system that permitted concentration of aliquots of end-exhaled air (alveolar air) from one or more exhalations in a tube packed with activated charcoal, which was then desorbed with carbon sulfide and analyzed by gas chromatography. Concentrations of n-hexane in breathing zone air were significantly correlated with urinary concentrations of 2,5-hexanedione ( r = 0.88) and with exhaled air n-hexane ( r = 0.86); in addition, the two biological indicators correlated significantly ( r = 0.70). Analyses in both exhaled air and urine were thus considered useful for biological monitoring of the risk of exposure to n-hexane. [ABSTRACT FROM AUTHOR]