Publications by authors named "Patrik Spanel"

133 Publications

Ligand Switching Ion Chemistry: An SIFDT Case Study of the Primary and Secondary Reactions of Protonated Acetic Acid Hydrates with Acetone.

J Am Soc Mass Spectrom 2021 Jul 20. Epub 2021 Jul 20.

J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 2155/3, 18223 Prague 8, Czech Republic.

A study was performed of the reactions of protonated acetic acid hydrates, CHCOOHH(HO), with acetone molecules, CHCOCH, using a selected ion flow-drift tube (SIFDT). The rationale for this study is that hydrated protonated organic molecules are major product ions in secondary electrospray ionization mass spectrometry (SESI-MS) and ion mobility spectrometry (IMS). Yet the formation and reactivity of these hydrates are only poorly understood, and kinetics data are only sparse. The existing SIFDT instrument in our laboratory was upgraded to include an octupole ion guide and a separate drift tube by which hydrated protonated ions can be selectively injected into the drift tube reactor and their reactions with molecules studied under controlled conditions. This case study shows that, in these hydrated ion reactions with acetone molecules, the dominant reaction process is ligand switching producing mostly proton-bound dimer ions (CHCOCH)H(CHCOOH), with minor branching into (CHCOCH)H(HO). This switching reaction was observed to proceed at the collisional rate, while other studied hydrated ions reacted more slowly. An attempt is made to understand the reaction mechanisms and the structures of the reaction intermediate ions at the molecular level. Secondary switching reactions of the asymmetric proton-bound dimer ions lead to a formation of strongly bound symmetrical dimers (CHCOCH)H, the terminating ion in this ion chemistry. These results strongly suggest that, in SESI-MS and IMS, the presence of a polar compound, like acetone in exhaled breath, can suppress the analyte ions of low concentration compounds like acetic acid thus compromising their quantification.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/jasms.1c00174DOI Listing
July 2021

Selected ion flow tube mass spectrometry for targeted analysis of volatile organic compounds in human breath.

Nat Protoc 2021 07 4;16(7):3419-3438. Epub 2021 Jun 4.

Department of Surgery and Cancer, Imperial College London, London, UK.

The analysis of volatile organic compounds (VOCs) within breath for noninvasive disease detection and monitoring is an emergent research field that has the potential to reshape current clinical practice. However, adoption of breath testing has been limited by a lack of standardization. This protocol provides a comprehensive workflow for online and offline breath analysis using selected ion flow tube mass spectrometry (SIFT-MS). Following the suggested protocol, 50 human breath samples can be analyzed and interpreted in <3 h. Key advantages of SIFT-MS are exploited, including the acquisition of real-time results and direct compound quantification without need for calibration curves. The protocol includes details of methods developed for targeted analysis of disease-specific VOCs, specifically short-chain fatty acids, aldehydes, phenols, alcohols and alkanes. A procedure to make custom breath collection bags is also described. This standardized protocol for VOC analysis using SIFT-MS is intended to provide a basis for wider application and the use of breath analysis in clinical studies.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41596-021-00542-0DOI Listing
July 2021

Cross Platform Analysis of Volatile Organic Compounds Using Selected Ion Flow Tube and Proton-Transfer-Reaction Mass Spectrometry.

J Am Soc Mass Spectrom 2021 May 8;32(5):1215-1223. Epub 2021 Apr 8.

Department of Surgery and Cancer, Imperial College London, St. Mary's Hospital, London W2 1PE, United Kingdom.

Volatile breath metabolites serve as potential disease biomarkers. Online mass spectrometry (MS) presents real-time quantification of breath volatile organic compounds (VOCs). The study aims to assess the relationship between two online analytical mass spectrometry techniques in the quantification of target breath metabolites: selected ion flow tube mass spectrometry (SIFT-MS) and proton-transfer-reaction time-of-flight mass spectrometry (PTR-ToF-MS). The two following techniques were employed: (i) direct injection with bag sampling using SIFT-MS and PTR-ToF-MS and (ii) direct injection and thermal desorption (TD) tube comparison using PTR-ToF-MS. The concentration of abundant breath metabolites, acetone and isoprene, demonstrated a strong positive linear correlation between both mass spectrometry techniques ( = 0.97, = 0.89, respectively; < 0.001) and between direct injection and TD tube ( = 0.97, = 0.92, respectively; < 0.001) breath sampling techniques. This was reflected for the majority of short chain fatty acids and alcohols tested ( > 0.80, < 0.001). Analyte concentrations were notably higher with the direct injection of a sampling bag compared to the TD method. All metabolites produced a high degree of agreement in the detection range of VOCs between SIFT-MS and PTR-ToF-MS, with the majority of compounds falling within 95% of the limits of agreement with Bland-Altman analysis. The cross platform analysis of exhaled breath demonstrates strong positive correlation coefficients, linear regression, and agreement in target metabolite detection rates between both breath sampling techniques. The study demonstrates the transferability of using data outputs between SIFT-MS and PTR-ToF-MS. It supports the implementation of a TD platform in multi-site studies for breath biomarker research in order to facilitate sample transport between clinics and the laboratory.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/jasms.1c00027DOI Listing
May 2021

Reagent and analyte ion hydrates in secondary electrospray ionization mass spectrometry (SESI-MS), their equilibrium distributions and dehydration in an ion transfer capillary: Modelling and experiments.

Rapid Commun Mass Spectrom 2021 Apr;35(7):e9047

J. Heyrovsky Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 3, Prague 8, 18223, Czech Republic.

Rationale: Secondary electrospray ionization (SESI) in a water spray environment at atmospheric pressure involves the reactions of hydrated hydronium reagent ions, H O (H O) , with trace analyte compounds in air samples. Understanding the formation and dehydration of reagent and analyte ions is the foundation for meaningful quantification of trace compounds by SESI-mass spectrometry (MS).

Methods: A numerical model based on gas-phase ion thermochemistry is developed that describes equilibria in H O (H O) reagent cluster ion distributions and ligand switching reactions with polar NH molecules leading to equilibrated hydrated ammonium ions NH (H O) . The model predictions are compared with experimental results obtained using a cylindrical SESI source coupled to an ion-trap mass spectrometer via a heated ion transfer capillary. Non-polar isoprene, C H , was used to further probe the nature of the reagent ions.

Results: Equilibrium distributions of H O (H O) ions and their reactions with NH molecules have been characterized by the model in the near-atmospheric pressure SESI source. NH analyte molecules displace H O ligands from the H O (H O) ions at the collisional rate forming NH (H O) ions, which travel through the heated ion transfer capillary losing H O molecules. The data for variable NH concentrations match the model predictions and the C H test substantiates the notion of dehydration in the heated capillary.

Conclusions: Large cluster ions formed in the SESI region are dehydrated to H O (H O) and NH (H O) while passing through the heated capillary, and considerable diffusion losses also occur. This phenomenon is also predicted for other polar analyte molecules, A, that can undergo similar switching reactions, thus forming AH and AH (H O) analyte ions.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/rcm.9047DOI Listing
April 2021

Parallel secondary electrospray ionisation mass spectrometry and selected ion flow tube mass spectrometry quantification of trace amounts of volatile ketones.

Rapid Commun Mass Spectrom 2021 Feb;35(4):e8981

J. Heyrovsky Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 3, Prague 8, 18223, Czech Republic.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/rcm.8981DOI Listing
February 2021

The development of a fully integrated 3D printed electrochemical platform and its application to investigate the chemical reaction between carbon dioxide and hydrazine.

Electrochim Acta 2020 Nov 24;360:136984. Epub 2020 Aug 24.

J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 3, 18223 Prague, Czechia.

The combination of computer assisted design and 3D printing has recently enabled fast and inexpensive manufacture of customized 'reactionware' for broad range of electrochemical applications. In this work bi-material fused deposition modeling 3D printing is utilized to construct an integrated platform based on a polyamide electrochemical cell and electrodes manufactured from a polylactic acid-carbon nanotube conductive composite. The cell contains separated compartments for the reference and counter electrode and enables reactants to be introduced and inspected under oxygen-free conditions. The developed platform was employed in a study investigating the electrochemical oxidation of aqueous hydrazine coupled to its bulk reaction with carbon dioxide. The analysis of cyclic voltammograms obtained in reaction mixtures with systematically varied composition confirmed that the reaction between hydrazine and carbon dioxide follows 1/1 stoichiometry and the corresponding equilibrium constant amounts to (2.8 ± 0.6) × 10. Experimental characteristics were verified by results of numerical simulations based on the finite-element-method.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.electacta.2020.136984DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7444954PMC
November 2020

Understanding Gas Phase Ion Chemistry Is the Key to Reliable Selected Ion Flow Tube-Mass Spectrometry Analyses.

Anal Chem 2020 10 9;92(19):12750-12762. Epub 2020 Sep 9.

J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 3, 18223 Prague 8, Czech Republic.

Ion-molecule reactions (IMR) are at the very core of trace gas analyses in modern chemical ionization (CI) mass spectrometer instruments, which are increasingly being used in diverse areas of research and industry. The focus of this Perspective is on the ion chemistry that underpins gas-phase analytical CI methods. Special attention is given to the soft chemical ionization method known as selected ion flow tube-mass spectrometry (SIFT-MS). The processes involved in the ion chemistry of the reagent cations, HO, NO, and O, and the anions, O, O, OH, and NO, are discussed in some detail. Stressed throughout is that an understanding of these processes is mandatory to obtain reliable analyses of humid gaseous media such as ambient air and exhaled breath. It is indicated that further research is needed to understand the consequences of replacing helium in some situations by the more readily available nitrogen as the carrier gas in SIFT-MS.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.analchem.0c03050DOI Listing
October 2020

Ion chemistry of phthalates in selected ion flow tube mass spectrometry: isomeric effects and secondary reactions with water vapour.

Phys Chem Chem Phys 2020 Jul;22(28):16345-16352

J. Heyrovský Institute of Physical Chemistry of the CAS, v. v. i. Dolejškova 2155/3, 182 23 Prague, Czech Republic. [email protected]

Phthalates are widely industrially used and their toxicity is of serious environmental and public health concern. Chemical ionization (CI) analytical techniques offer the potential to detect and monitor traces of phthalate vapours in air or sample headspace in real time. Promising techniques include selected ion flow tube mass spectrometry (SIFT-MS), proton transfer reaction mass spectrometry (PTR-MS) and ion mobility spectrometry (IMS). To facilitate such analyses, reactions of H3O+, O2+ and NO+ reagent ions with phthalate molecules need to be understood. Thus, the ion chemistry of dimethyl phthalate isomers (dimethyl phthalate, DMP - ortho; dimethyl isophthalate, DMIP - meta; dimethyl terephthalate, DMTP - para), diethyl phthalate (DEP), dipropyl phthalate (DPP) and dibutyl phthalate (DBP) was studied by SIFT-MS. Reactions of H3O+, O2+ and NO+ with these phthalate molecules M were found to produce the characteristic primary ion products MH+, M+ and MNO+, respectively. In addition, a dissociation process forming the (M-OR)+ fragment was observed. For phthalates with longer alkyl chains, mainly DPP and DBP, a secondary dissociation channel triggered by the McLafferty rearrangement was also observed. However, this is dominant only for the more energetic O2+ reactions with phthalates, additionally resulting in a recognisable formation of the protonated phthalate anhydride. For the NO+ reagent ions, the McLafferty rearrangement makes only a minor contribution and for H3O+, it was not observed. Experiments on the effect of water vapour on this ion chemistry have shown that protonated DMIP and DMTP efficiently associate with H2O forming the DMIP·H+H2O, DMIP·H+(H2O)2 and DMTP·H+H2O cluster ions, whilst the protonated ortho DMP isomer as well as other ortho phthalates DEP, DPP and DBP does not associate with H2O. The results indicate that the degree of hydration can be used to identify specific phthalate isomers in CI.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1039/d0cp00538jDOI Listing
July 2020

Chemical ionization of glyoxal and formaldehyde with HO ions using SIFT-MS under variable system humidity.

Phys Chem Chem Phys 2020 May;22(18):10170-10178

J. Heyrovsky Institute of Physical Chemistry of the CAS, v. v. i, Dolejškova 2155/3, 182 23 Prague, Czech Republic. [email protected]

Glyoxal (C2H2O2) is a highly reactive molecule present at trace levels in specific gaseous environments. For analyses by chemical ionization mass spectrometry, it is important to understand the gas-phase chemistry initiated by reactions of H3O+ ions with C2H2O2 molecules in the presence of water vapour. This chemistry was studied at variable humidity using a selected ion flow tube, SIFT. The initial step is a proton transfer reaction forming protonated glyoxal C2H3O2+. The second step, in the presence of water vapour, is the association forming C2H3O2+(H2O) and interestingly also protonated formaldehyde CH2OH+. Hydrated protonated formaldehyde CH2OH+(H2O) was also observed. Relative signals of these four ionic products were studied at the end of the flow tube where the reactions took place during 0.3 ms in helium carrier gas (1.5 mbar, 300 K) as the water vapour number density varied up to 1014 cm-3. The data were interpreted using numerical kinetics modelling of the reaction sequences and the mechanisms and kinetics of the reaction steps were characterised. The results thus facilitate SIFT-MS analyses of glyoxal in humid air whilst drawing attention to ion overlaps with formaldehyde products.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1039/d0cp00297fDOI Listing
May 2020

Selected ion flow tube mass spectrometry analyses of isobaric compounds methanol and hydrazine in humid air.

Rapid Commun Mass Spectrom 2020 May;34(10):e8744

J. Heyrovsky Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 3, Prague 8, 18223, Czech Republic.

Rationale: The volatile compounds generated by the electrochemical reduction of atmospheric carbon dioxide and nitrogen include isobaric methanol (CH OH) and, potentially, hydrazine (N H ). To achieve quantification of hydrazine molecules by selected ion flow tube mass spectrometry (SIFT-MS), its reactions with H O , NO and O reagent ions must be understood.

Methods: A SIFT study (using a SIFT-MS instrument) was carried out to obtain rate coefficients and product ions for the reactions of H O , NO and O reagent ions with N H and CH OH molecules present in the humid headspace of their aqueous solutions. Using the kinetics data obtained, solution headspace concentrations were determined for both compounds as a function of their liquid-phase concentrations at 10, 20 and 35°C.

Results: Both compounds react with H O ions via rapid proton transfer to produce CH OH and H N ions with the common m/z value of 33. It is revealed that NO rapidly transfers charge to N H (rate coefficient k = 2.3 × 10 cm s ) but only slowly associates with CH OH (k  = 7.1 × 10 cm s ). Thus, selective analysis can be achieved using both H O and NO reagent ions. The headspace methanol vapour concentration was found to increase with increasing solution temperature, but that of hydrazine decreased with an associated increase of ammonia (NH ) as measured with O reagent ions.

Conclusions: The isobaric compounds methanol and hydrazine can be separately analysed in real time by SIFT-MS using H O and NO reagent ions, even when they co-occur in humid air. The evolution of hydrazine from aqueous solutions can be quantitatively monitored together with its decomposition at elevated temperatures.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/rcm.8744DOI Listing
May 2020

Impact of oral cleansing strategies on exhaled volatile organic compound levels.

Rapid Commun Mass Spectrom 2020 May;34(9):e8706

Department of Surgery and Cancer, Imperial College London, St Mary's Hospital, London, UK.

Rationale: The analysis of volatile organic compounds (VOCs) within exhaled breath potentially offers a non-invasive method for the detection and surveillance of human disease. Oral contamination of exhaled breath may influence the detection of systemic VOCs relevant to human disease. This study aims to assess the impact of oral cleansing strategies on exhaled VOC levels in order to standardise practice for breath sampling.

Methods: Ten healthy volunteers consumed a nutrient challenge followed by four oral cleansing methods: (a) water, (b) saltwater, (c) toothbrushing, and (d) alcohol-free mouthwash. Direct breath sampling was performed using selected ion flow tube mass spectrometry after each intervention.

Results: Proposed reactions suggest that volatile fatty acid and alcohol levels (butanoic, pentanoic acid, ethanol) declined with oral cleansing interventions, predominantly after an initial oral rinse with water. Concentrations of aldehydes and phenols (acetaldehyde, menthone, p-cresol) declined with oral water rinse; however, they increased after toothbrushing and mouthwash use, secondary to flavoured ingredients within these products. No significant reductions were observed with sulphur compounds.

Conclusions: Findings suggest that oral rinsing with water prior to breath sampling may reduce oral contamination of VOC levels, and further interventions for oral decontamination with flavoured products may compromise results. This intervention may serve as a simple and inexpensive method of standardisation within breath research.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/rcm.8706DOI Listing
May 2020

Volatile compounds released by Nalophan; implications for selected ion flow tube mass spectrometry and other chemical ionisation mass spectrometry analytical methods.

Rapid Commun Mass Spectrom 2020 Mar;34(5):e8602

J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Dolejškova, Czech Republic.

Nalophan bags are commonly used to collect breath samples for volatile metabolite analysis. Volatile organic compounds (VOCs) released from the polymer can, however, be mistaken as breath metabolites when analyses are performed by selected ion flow tube mass spectrometry, SIFT-MS, or techniques that depend on a proper understanding of ion chemistry.

Methods: Three analytical techniques were used to analyse the VOCs released into the nitrogen used to expand Nalophan bags, viz. gas chromatography/mass spectrometry (GC/MS), secondary electrospray ionization mass spectrometry (SESI-MS) and selected ion flow tube mass spectrometry (SIFT-MS). The most significant VOCs were identified and quantified by SIFT-MS as a function of storage time, temperature and humidity.

Results: The consistent results obtained by these three analytical methods identify 1,2-ethanediol (ethylene glycol) and 2-methyl-1,3-dioxolane as the major VOCs released by the Nalophan. Their concentrations are enhanced by increasing the bag storage temperature and time, reaching 170 parts-per-billion by volume (ppbv) for ethylene glycol and 34 ppbv for 2-methyl-1,3-dioxolane in humid nitrogen (absolute humidity of 5%) contained in an 8-L Nalophan bag stored at 37°C for 160 min.

Conclusions: Using H O reagent ions for SIFT-MS and SESI-MS analyses, the following analyte ions (m/z values) are affected by the Nalophan impurities: 45, 63, 81, 89 and 99, which can compromise analyses of acetaldehyde, ethylene glycol, monoterpenes, acetoin, butyric acid, hexanal and heptane.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/rcm.8602DOI Listing
March 2020

Styrene radical cations for chemical ionization mass spectrometry analyses of monoterpene hydrocarbons.

Rapid Commun Mass Spectrom 2019 Dec;33(24):1870-1876

J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 3, 18223, Prague, Czech Republic.

Rationale: Monoterpene hydrocarbons play an important role in the formation of secondary aerosol particles and in atmospheric chemistry. Thus, there is a demand to measure their individual concentrations in situ in real time. Currently, only the total concentration of monoterpenes C H can be determined by chemical ionization mass spectrometry techniques using reagent ions H O , NO and (C H ) without gas chromatographic separation.

Methods: The styrene cation C H was investigated as a reagent for chemical ionization of monoterpenes. The modified selected ion flow drift tube, SIFDT, technique was used to characterize the differences in product ion distributions between α-phellandrene, α-pinene, γ-terpinene, β-pinene, ocimene, sabinene, 3-carene, (R)-limonene, camphene and myrcene.

Results: The monoterpene molecular cation C H is the main product (about 90%) for all isomers except (R)-limonene and camphene with an efficient channel of C H C H adduct formation and γ-terpinene with unexpectedly significant product ions at m/z 134 and 135 corresponding to losses of H and H.

Conclusions: Utilization of the styrene cation for the ionization of monoterpenes is beneficial due to the very low fragmentation of the product ions. Specific association product ions for camphene and (R)-limonene and fragment product ions for γ-terpinene allow them to be distinguished from other isomers that produce mostly the molecular cation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/rcm.8556DOI Listing
December 2019

Time-integrated thermal desorption for quantitative SIFT-MS analyses of atmospheric monoterpenes.

Anal Bioanal Chem 2019 May 11;411(14):2997-3007. Epub 2019 Apr 11.

The Czech Academy of Sciences, J. Heyrovský Institute of Physical Chemistry, Dolejškova 3, 18223, Prague 8, Czech Republic.

A new time-integrated thermal desorption technique has been developed that can be used with selected ion flow tube mass spectrometry, TI-TD/SIFT-MS, for off-line quantitative analyses of VOCs accumulated onto sorbents. Using a slow desorption temperature ramp, the absolute amounts of desorbed compounds can be quantified in real time by SIFT-MS and constitutional isomers can be separated. To facilitate application of this technique to environmental atmospheric monitoring, method parameters were optimised for quantification of the three common atmospheric monoterpenes: β-pinene, R-limonene and 3-carene. Three sorbent types, Tenax TA, Tenax GR and Porapak Q, were tested under 26 different desorption conditions determined by the "design of experiment", DOE, systematic approach. The optimal combination of type of sorbent, bed length, sampling flow rate, sample volume and the initial desorption temperature was determined from the experimental results by ANOVA. It was found that Porapak Q exhibited better efficiency of sample collection and further extraction for total monoterpene concentration measurements. On the other hand, Tenax GR or TA enabled separation of all three monoterpenes. The results of this laboratory study were tested with the sample accumulated from a branch of a Pinus nigra tree. Graphical abstract.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00216-019-01782-6DOI Listing
May 2019

Electrostatic Switching and Selection of HO, NO, and O Reagent Ions for Selected Ion Flow-Drift Tube Mass Spectrometric Analyses of Air and Breath.

Anal Chem 2019 04 27;91(8):5380-5388. Epub 2019 Mar 27.

J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences , Dolejškova 3 , 18223 Prague 8 , Czech Republic.

Soft chemical ionization mass spectrometry techniques, particularly the well-established proton transfer reaction mass spectrometry, PTR-MS, and selected ion flow tube mass spectrometry, SIFT-MS, are widely used for real-time quantification of volatile organic compounds in ambient air and exhaled breath with applications ranging from environmental science to medicine. The most common reagent ions HO, NO, or O can be selected either by quadrupole mass filtering from a discharge ion source, which is relatively inefficient, or by switching the gas/vapor in the ion source, which is relatively slow. The chosen reagent ions are introduced into a flow tube or flow-drift tube reactor where they react with analyte molecules in sample gas. This article describes a new electrostatic reagent ion switching, ERIS, technique by which HO, NO, and O reagent ions, produced simultaneously in three separate gas discharges, can be purified in post-discharge source drift tubes, switched rapidly, and selected for transport into a flow-drift tube reactor. The construction of the device and the ion-molecule chemistry exploited to purify the individual reagent ions are described. The speed and sensitivity of ERIS coupled to a selected ion flow-drift tube mass spectrometry, SIFDT-MS, is demonstrated by the simultaneous quantification of methanol with HO, acetone with NO, and dimethyl sulfide with O reagent ions in single breath exhalations. The present ERIS approach is shown to be preferable to the previously used quadrupole filtering, as it increases analytical sensitivity of the SIFDT-MS instrument while reducing its size and the required number of vacuum pumps.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.analchem.9b00530DOI Listing
April 2019

Increase of the Charge Transfer Rate Coefficients for NO and O Reactions with Isoprene Molecules at Elevated Interaction Energies.

J Phys Chem A 2018 Dec 11;122(51):9733-9737. Epub 2018 Dec 11.

J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences , Dolejškova 3 , 18223 Prague 8 , Czech Republic.

Atmospheric concentrations of isoprene (2-methylbutadiene) in environmental research and in exhaled breath for medical research are usually measured by soft chemical ionization mass spectrometry that relies on a knowledge of the kinetics of the gas phase reactions of HO, NO or O ions with isoprene molecules. Thus, we have carried out an experimental study of the rate coefficients, k, and product ions distributions for such reactions over a range of ion-molecule interaction energy, E, (0.05-0.8 eV) in a helium-buffered selected ion flow-drift tube, SIFDT. It is found that contrary to the ion-induced dipole capture model, k for the NO and O charge transfer reactions almost doubled over the E range, while k for the HO proton transfer reaction did not significantly change with E , as predicted. These results reveal that the reaction mechanism involving ion-molecule capture forming an intermediate complex does not properly describe charge transfer to isoprene molecules. It is important to account for this increase in k with E in these isoprene charge transfer reactions, and probably for other such reactions, when using drift tube reactors for trace gas analysis.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.jpca.8b08580DOI Listing
December 2018

Evaluation of lipid peroxidation by the analysis of volatile aldehydes in the headspace of synthetic membranes using Selected Ion Flow Tube Mass Spectrometry, SIFT-MS.

Rapid Commun Mass Spectrom 2018 Jun 23. Epub 2018 Jun 23.

J. Heyrovsky Institute of Physical Chemistry of Science, Academy of Science of the Czech Republic, Dolejškova 3, 18223, Prague 8, Czech Republic.

Rationale: Oxidative stress of cell membranes leads to a number of pathological processes associated with some diseases and is accompanied by the release of volatile aldehydes, which, potentially, can be used as biomarkers. Thus, the aim was to investigate peroxidation of defined synthetic membranes by direct quantitative analysis of volatile aldehydes.

Methods: The concentration spectra of volatile compounds present in the headspace of synthetic membranes under peroxidation stress and following mechanical stress due to sonication were obtained using solid phase microextraction (SPME) in combination with Gas Chromatography Mass Spectrometry (SPME/GC/MS) and Selected Ion Flow Tube Mass Spectrometry (SIFT-MS). The focus was on the direct, real time quantification of volatile aldehydes. In addition, the total aldehydes in the aqueous membrane suspensions were quantified using the TBARS method.

Results: Propanal, butanal, pentanal, hexanal, heptanal and malondialdehyde were detected and quantified in the humid headspace of the media containing the synthetic membranes following peroxidation. The composition and concentration of these saturated aldehydes strongly depend on the unsaturated fatty acids representation in the liposomes. Some protective effect of cholesterol was observed especially for membranes peroxidised by Fenton reagents and after application of a mechanical stress.

Conclusions: This study demonstrates that peroxidation of model synthetic membranes in vitro can be tracked in real time using direct quantification by SIFT-MS of several specific aldehydes in the headspace of the membrane suspensions. Cholesterol plays an important role in retaining membrane structure and can indirectly protect membranes from lipid peroxidation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/rcm.8212DOI Listing
June 2018

Variation in Exhaled Acetone and Other Ketones in Patients Undergoing Bariatric Surgery: a Prospective Cross-sectional Study.

Obes Surg 2018 08;28(8):2439-2446

Department of Surgery and Cancer, Imperial College London, St Marys Hospital, London, UK.

Background: Dietary restriction together with alteration of the gastrointestinal tract results in major metabolic changes and significant weight loss in patients undergoing bariatric surgery. Current methods of measuring these changes are often inaccurate and lack a molecular basis. The objective of this study was to determine the role of exhaled ketones as non-invasive markers of nutritional status in patients undergoing surgical treatment of obesity.

Methods: Patients at different stages of treatment for obesity were recruited to this single-centre cross-sectional study. The sample time points were as follows: (i) at the time of initial attendance prior to dietary or surgical interventions, (ii) on the day of surgery following a low carbohydrate diet, and (iii) > 3 months after either Roux-en-Y gastric bypass or sleeve gastrectomy. The concentrations of ketones within breath samples were analysed by selected ion flow tube mass spectrometry.

Results: Forty patients were recruited into each of the three study groups. Exhaled acetone concentrations increased significantly following pre-operative diet (1396 ppb) and bariatric surgery (1693 ppb) compared to the start of treatment (410 ppb, P < 0.0001). In comparison, concentrations of heptanone (6.5 vs. 4.1 vs. 1.4 ppb, P = 0.021) and octanone (3.0 vs. 1.4 vs. 0.7 ppb, P = 0.021) decreased significantly after dieting and surgical intervention. Exhaled acetone (ρ - 0.264, P = 0.005) and octanone (ρ 0.215, P = 0.022) concentrations were observed to correlate with excess body weight at the time of sampling. Acetone and octanone also correlated with neutrophil and triglyceride levels (P < 0.05).

Conclusion: Findings confirm breath ketones, particularly acetone, to be a potentially clinically useful method of non-invasive nutritional assessment in obese patients.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s11695-018-3180-5DOI Listing
August 2018

Quantification of volatile compounds released by roasted coffee by selected ion flow tube mass spectrometry.

Rapid Commun Mass Spectrom 2018 May;32(9):739-750

J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, v.v.i., Dolejškova 3, 182 23, Prague 8, Czech Republic.

Rationale: The major objective of this exploratory study was to implement selected ion flow tube mass spectrometry, SIFT-MS, as a method for the on-line quantification of the volatile organic compounds, VOCs, in the headspace of the ground roasted coffee.

Methods: The optimal precursor ions and characteristic analyte ions were selected for real-time SIFT-MS quantification of those VOCs that are the most abundant in the headspace or known to contribute to aroma. NO reagent ion reactions were exploited for most of the VOC analyses. VOC identifications were confirmed using gas chromatography/mass spectrometry, GC/MS, coupled with solid-phase microextraction, SPME.

Results: Thirty-one VOCs were quantified, including several alcohols, aldehydes, ketones, carboxylic acids, esters and some heterocyclic compounds. Variations in the concentrations of each VOC in the seven regional coffees were typically less than a factor of 2, yet concentrations patterns characteristic of the different regional coffees were revealed by heat map and principal component analyses. The coefficient of variation in the concentrations across the seven coffees was typically below 24% except for furfural, furan, methylfuran and guaiacol.

Conclusions: The SIFT-MS analytical method can be used to quantify in real time the most important odoriferous VOCs in ground coffee headspace to sufficient precision to reveal some differences in concentration patterns for coffee produced in different countries.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/rcm.8095DOI Listing
May 2018

Ion chemistry at elevated ion-molecule interaction energies in a selected ion flow-drift tube: reactions of HO, NO and O with saturated aliphatic ketones.

Phys Chem Chem Phys 2017 Dec;19(47):31714-31723

J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 3, 18223 Prague 8, Czech Republic.

The reactions of HO, NO and O ions with a homologous series of six aliphatic ketones, viz. acetone through 2-octanone, have been investigated in a helium-buffered selected ion flow-drift tube, SIFDT, in order to reveal their dependencies on ion-molecule interaction energies, E, and to gain insight into their mechanisms. The ultimate motivation is to allow analysis and absolute quantification of trace amounts of ketones and other volatile organic compounds in air using selected ion flow-drift tube mass spectrometry, SIFDT-MS. The reactions of HO with the ketone molecules, M, proceed via exothermic proton transfer producing MH ions, the collisional rate coefficients, k, for which can be calculated as a function of E and are seen to reduce by about one third over the E range from 0.05 eV up to 0.5 eV. The rate coefficients, k, and product ion distributions for the NO and O reactions with M had to be obtained experimentally relative to the calculated k for the HO reactions. The product ions of the NO/ketones reactions initially proceed via the formation of excited (NOM)* adduct ions that partially fragment, and the k reduces with E as much as four times for the acetone reactions but remains close to their respective k for the higher-order ketones indicating long lifetimes of the (NOM)* ions with respect to the stabilising collision times with He atoms. The k for the O/ketones dissociative charge transfer reactions are observed to be greater than their calculated k implying that long distance electron transfer occurs.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1039/c7cp05795dDOI Listing
December 2017

What is the real utility of breath ammonia concentration measurements in medicine and physiology?

J Breath Res 2018 01 3;12(2):027102. Epub 2018 Jan 3.

J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, v.v.i., Dolejškova 3, 182 23 Prague 8, Czechia.

Much effort continues to be devoted to the development of devices to analyse breath ammonia with the anticipation that breath ammonia analyses will be useful in clinical practice. In this perspective we refer to the analytical techniques that have been used to measure breath ammonia, focusing on selected ion flow tube mass spectrometry, SIFT-MS, of which we have special knowledge and understanding. From the collected data obtained using the different techniques, we exam the origins of mouth- and nose-exhaled ammonia and conclude that mouth-exhaled ammonia is always elevated above a concentration that would be equilibrated with blood ammonia and is largely produced by the action of enzymes on salivary urea. Support to this conclusion is given by the reasonable correlation between blood urea concentration and mouth-exhaled ammonia concentration. Further, it is discussed that nose-exhaled ammonia largely originates at the alveolar interface and so its concentration more closely relates to the expected alveolar blood ammonia concentration. Ingestion of proteins results in increased blood/saliva urea and ultimately mouth-exhaled ammonia as does the generation of urease by H. pylori infection. It is also concluded that when mouth-exhaled ammonia is elevated then it may be due to either abnormally high blood urea, a high pH of the saliva/mouth/airways mucosa, poor oral hygiene or a combinations of these.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1088/1752-7163/aa907fDOI Listing
January 2018

Pentane and other volatile organic compounds, including carboxylic acids, in the exhaled breath of patients with Crohn's disease and ulcerative colitis.

J Breath Res 2017 11 29;12(1):016002. Epub 2017 Nov 29.

J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Dolejškova 3, 182 23 Prague 8, Czechia.

A study has been carried out on the volatile organic compounds (VOCs) in the exhaled breath of patients suffering from inflammatory bowel disease (IBD), comprising 136 with Crohn's disease (CD) and 51 with ulcerative colitis (UC), together with a cohort of 14 healthy persons as controls. Breath samples were collected by requesting the patients to inflate Nalophan bags, which were then quantitatively analysed using selected ion flow tube mass spectrometry (SIFT-MS). Initially, the focus was on n-pentane that had previously been quantified in single exhalations on-line to SIFT-MS for smaller cohorts of IBD patients. It was seen that the median concentration of pentane was elevated in the bag breath samples of the IBD patients compared to those of the healthy controls, in accordance with the previous study. However, the absolute median pentane concentrations in the bag samples were about a factor of two lower than those in the directly analysed single exhalations-a good illustration of the dilution of VOCs in the samples of breath collected into bags. Accounting for this dilution effect, the concentrations of the common breath VOCs, ethanol, propanol, acetone and isoprene, were largely as expected for healthy controls. The concentrations of the much less frequently measured hydrogen sulphide, acetic acid, propanoic acid and butanoic acid were seen to be more widely spread in the exhaled breath of the IBD patients compared to those for the healthy controls. The relative concentrations of pentane and these other VOCs weakly correlate with simple clinical activity indices. It is speculated that, potentially, hydrogen sulphide and these carboxylic acids could be exhaled breath biomarkers of intestinal bacterial overgrowth, which could assist therapeutic intervention and thus alleviate the symptoms of IBD.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1088/1752-7163/aa8468DOI Listing
November 2017

On the importance of accurate quantification of individual volatile metabolites in exhaled breath.

J Breath Res 2017 Nov 1;11(4):047106. Epub 2017 Nov 1.

Trans Spectra Limited, 9 The Elms, Newcastle under Lyme, United Kingdom.

It is argued that shortcomings of certain approaches to breath analysis research based on superficial interpretation of non-quantitative data are inadvertently inhibiting the progression of non-invasive breath analysis into clinical practice. The objective of this perspective is to suggest more clinically profitable approaches to breath research. Thus, following a discourse on the challenges and expectations in breath research, a brief indication is given of the analytical techniques currently used for the analysis of very humid exhaled breath. The seminal work that has been carried out using GC-MS revealed that exhaled breath comprises large numbers of trace volatile organic compounds, VOCs. Unfortunately, analysis of these valuable GC-MS data is mostly performed using chemometrics to distinguish the VOC content of breath samples collected from patients and healthy controls, and reliable quantification of the VOCs is rarely deemed necessary. This limited approach ignores the requirements of clinically acceptable biomarkers and misses the opportunity to identify relationships between the concentrations of individual VOCs and certain related physiological or metabolic parameters. Therefore, a plea is made for more effort to be directed towards the positive identification and accurate quantification of individual VOCs in exhaled breath, which are more physiologically meaningful as best exemplified by the quantification of breath nitric oxide, NO. Support for the value of individual VOC quantification is illustrated by the SIFT-MS studies of breath hydrogen cyanide, HCN, a biomarker of Pseudomonas aeruginosa infection, breath acetic acid as an indicator of airways acidification in cystic fibrosis patients, and n-pentane as a breath biomarker of inflammation in idiopathic bowel disease patients. These single VOCs could be used as non-invasive monitors of the efficacy of therapeutic intervention. The increase of breath methanol following the ingestion of a known amount of the sweetener aspartame impressively shows that accurate breath analysis is a reliable indicator of blood concentrations. However, using individual VOCs for specific disease diagnosis does have its problems and it is, perhaps, more appropriate to see their concentrations as proxy markers of general underlying physiological change. We dedicate this perspective to Lars Gustafsson for his seminal work on breath research and especially for his pioneering work on nitric oxide measurements in exhaled breath in asthma, which best shows the utility and value of the quantification of individual breath biomarkers on which this perspective focuses.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1088/1752-7163/aa7ab5DOI Listing
November 2017

Evaluation of peroxidative stress of cancer cells in vitro by real-time quantification of volatile aldehydes in culture headspace.

Rapid Commun Mass Spectrom 2017 Aug;31(16):1344-1352

J. Heyrovsky Institute of Physical Chemistry of Science, Academy of Science of the Czech Republic, Dolejškova 3, 18223, Prague 8, Czech Republic.

Rationale: Peroxidation of lipids in cellular membranes results in the release of volatile organic compounds (VOCs), including saturated aldehydes. The real-time quantification of trace VOCs produced by cancer cells during peroxidative stress presents a new challenge to non-invasive clinical diagnostics, which as described here, we have met with some success.

Methods: A combination of selected ion flow tube mass spectrometry (SIFT-MS), a technique that allows rapid, reliable quantification of VOCs in humid air and liquid headspace, and electrochemistry to generate reactive oxygen species (ROS) in vitro has been used. Thus, VOCs present in the headspace of CALU-1 cancer cell line cultures exposed to ROS have been monitored and quantified in real time using SIFT-MS.

Results: The CALU-1 lung cancer cells were cultured in 3D collagen to mimic in vivo tissue. Real-time SIFT-MS analyses focused on the volatile aldehydes: propanal, butanal, pentanal, hexanal, heptanal and malondialdehyde (propanedial), that are expected to be products of cellular membrane peroxidation. All six aldehydes were identified in the culture headspace, each reaching peak concentrations during the time of exposure to ROS and eventually reducing as the reactants were depleted in the culture. Pentanal and hexanal were the most abundant, reaching concentrations of a few hundred parts-per-billion by volume, ppbv, in the culture headspace.

Conclusions: The results of these experiments demonstrate that peroxidation of cancer cells in vitro can be monitored and evaluated by direct real-time analysis of the volatile aldehydes produced. The combination of adopted methodology potentially has value for the study of other types of VOCs that may be produced by cellular damage.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/rcm.7911DOI Listing
August 2017

Acetic acid is elevated in the exhaled breath of cystic fibrosis patients.

J Cyst Fibros 2017 09 16;16(5):e17-e18. Epub 2017 Feb 16.

Institute for Science and Technology in Medicine, Medical School, Keele University, Thornburrow Drive, Hartshill, Stoke-on-Trent ST4 7QB, UK.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jcf.2017.02.001DOI Listing
September 2017

Selected ion flow tube study of the reactions of H O and NO with a series of primary alcohols in the presence of water vapour in support of selected ion flow tube mass spectrometry.

Rapid Commun Mass Spectrom 2017 Mar;31(5):437-446

Institute for Science and Technology in Medicine, School of Medicine, Keele University, Thornburrow Drive, Hartshill, Stoke-on-Trent ST4 7QB, UK.

Rationale: Alcohols are often present in foods and other biological media, including exhaled breath, urine and cell culture headspace. For their analysis by selected ion flow tube mass spectrometry (SIFT-MS), the ion chemistry initiated by the reactions of the reagent ions H O and NO with alcohol molecules in the presence of water molecules needs to be understood and quantitatively described.

Methods: The reactions of H O and NO ions have been studied with the primary alcohols, methanol, ethanol, 1-propanol, 1-butanol, 1-pentanol and 1-hexanol, under the conditions used for SIFT-MS analyses (1 Torr He; 0.1 Torr air sample; 300 K) and over a range of sample gas humidity from 1% to 5.5%.

Results: The H O reactions led to the formation of protonated alcohol molecules MH and their hydrates MH (H O) and (MH -H O) fragment ions. The NO reactions were observed to proceed mainly via hydride ion transfer, resulting in the formation of [M-H] product ions. Formation of the NO M adduct ions was also observed due to ligand switching between the NO (H O) hydrated reagent ions and M, and via direct NO /M association in the case of ethanol. The variation in the percentages of the hydrated product ions with the air sample humidity is reported.

Conclusions: This detailed study has provided the kinetics data, including the secondary hydrated ion product distributions, for the reactions of a number of volatile primary alcohols with the SIFT-MS reagent ions H O and NO , which allows their analyses by SIFT-MS in humid air and also helps in the interpretation of proton transfer reaction (PTR)-MS data. Copyright © 2016 John Wiley & Sons, Ltd.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/rcm.7811DOI Listing
March 2017

Exhaled breath hydrogen cyanide as a marker of early infection in children with cystic fibrosis.

ERJ Open Res 2015 Oct 16;1(2). Epub 2015 Nov 16.

Academic Department of Child Health, University Hospital of North Staffordshire, Stoke on Trent, UK; Institute of Science and Technology in Medicine, Keele University, Keele, UK.

Hydrogen cyanide is readily detected in the headspace above cultures and in the breath of cystic fibrosis (CF) patients with chronic () infection. We investigated if exhaled breath HCN is an early marker of infection. 233 children with CF who were free from infection were followed for 2 years. Their median (interquartile range) age was 8.0 (5.0-12.2) years. At each study visit, an exhaled breath sample was collected for hydrogen cyanide analysis. In total, 2055 breath samples were analysed. At the end of the study, the hydrogen cyanide concentrations were compared to the results of routine microbiology surveillance. was isolated from 71 children during the study with an incidence (95% CI) of 0.19 (0.15-0.23) cases per patient-year. Using a random-effects logistic model, the estimated odds ratio (95% CI) was 3.1 (2.6-3.6), which showed that for a 1- ppbv increase in exhaled breath hydrogen cyanide, we expected a 212% increase in the odds of infection. The sensitivity and specificity were estimated at 33% and 99%, respectively. Exhaled breath hydrogen cyanide is a specific biomarker of new infection in children with CF. Its low sensitivity means that at present, hydrogen cyanide cannot be used as a screening test for this infection.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1183/23120541.00044-2015DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5005121PMC
October 2015

Spectroscopic investigations of high-energy-density plasma transformations in a simulated early reducing atmosphere containing methane, nitrogen and water.

Phys Chem Chem Phys 2016 Oct;18(39):27317-27325

J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Dolejškova 3, 182 23 Prague 8, Czech Republic.

Large-scale plasma was created in gas mixtures containing methane using high-power laser-induced dielectric breakdown (LIDB). The composition of the mixtures corresponded to a cometary and/or meteoritic impact into the early atmosphere of either Titan or Earth. A multiple-centimeter-sized fireball was created by focusing a single 100 J, 450 ps near-infrared laser pulse into the center of a 15 L gas cell. The excited reaction intermediates formed during the various stages of the LIDB plasma chemical evolution were investigated using optical emission spectroscopy (OES) with temporal resolution. The chemical consequences of laser-produced plasma generation in a CH-N-HO mixture were investigated using high resolution Fourier-transform infrared absorption spectroscopy (FTIR) and gas selected ion flow tube spectrometry (SIFT). Several simple inorganic and organic compounds were identified in the reaction mixture exposed to ten laser sparks. Deuterated water (DO) in a gas mixture was used to separate several of the produced isotopomers of acetylene, which were then quantified using the FTIR technique.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1039/c6cp05025eDOI Listing
October 2016

Do linear logistic model analyses of volatile biomarkers in exhaled breath of cystic fibrosis patients reliably indicate Pseudomonas aeruginosa infection?

J Breath Res 2016 08 17;10(3):036013. Epub 2016 Aug 17.

J Heyrovský Institute of Physical Chemistry, The Czech Academy of Sciences, v.v.i., Dolejškova 3, 18223, Prague 8, Czech Republic.

Non-invasive breath analysis has been used to search for volatile biomarkers of lungs and airways infection by Pseudomonas aeruginosa, PA, in cystic fibrosis patients. The exhaled breath of 20 PA-infected patients and 38 PA-negative patients was analysed using selected ion flow tube mass spectrometry, SIFT-MS. Special attention was given to the positive identification and accurate quantification of 16 volatile compounds (VOCs) as assured by the detailed consideration of their analytical ion chemistry occurring in the SIFT-MS reactor. However, the diagnostic sensitivity and specificity of the concentrations of any of the 16 compounds taken individually were found to be low. But when a linear combination of the concentrations of all 16 VOCs was used to construct an optimised receiver operating characteristics (ROC) curve using a linear logistic model, the diagnostic separation of PA-infected patients relative to the PA-negative patients was apparently good in terms of the derived sensitivity (89%), specificity (86%), and the area under the ROC curve is 0.91. Four compounds were revealed by the linear logistic model as significant, viz. malondialdehyde, isoprene, phenol and acetoin. The implications of these results to PA detection in the airways are assessed. Whilst such a metabolomics approach to optimise the ROC curve is widely used in breath analysis, it can lead to misleading indications. Therefore, we conclude that the results of the linear logistic model analyses are of limited immediate clinical value. The identified compounds should rather be considered as a stimulus for further independent studies involving larger patient cohorts.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1088/1752-7155/10/3/036013DOI Listing
August 2016

Differentiation of pulmonary bacterial pathogens in cystic fibrosis by volatile metabolites emitted by their in vitro cultures: Pseudomonas aeruginosa, Staphylococcus aureus, Stenotrophomonas maltophilia and the Burkholderia cepacia complex.

J Breath Res 2016 08 10;10(3):037102. Epub 2016 Aug 10.

J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, v.v.i., Dolejškova 3, 182 23 Prague 8, Czech Republic.

As a contribution to the continuing search for breath biomarkers of lung and airways infection in patients with cystic fibrosis, CF, we have analysed the volatile metabolites released in vitro by Pseudomonas aeruginosa and other bacteria involved in respiratory infections in these patients, i.e. those belonging to the Burkholderia cepacia complex, Staphylococcus aureus or Stenotrophomonas maltophilia. These opportunistic pathogens are generally harmless to healthy people but they may cause serious infections in patients with severe underlying disease or impaired immunity such as CF patients. Volatile organic compounds emitted from the cultures of strains belonging to the above-mentioned four taxa were analysed by selected ion flow tube mass spectrometry. In order to minimize the effect of differences in media composition all strains were cultured in three different liquid media. Multivariate statistical analysis reveals that the four taxa can be well discriminated by the differences in the headspace VOC concentration profiles. The compounds that should be targeted in breath as potential biomarkers of airway infection were identified for each of these taxa of CF pathogens.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1088/1752-7155/10/3/037102DOI Listing
August 2016
-->