Journal of Breath Research

Publications in this journal

• Article: Potential sources of 2-aminoacetophenone to confound the Pseudomonas aeruginosa breath test, including analysis of a food challenge study

  A. Scott-Thomas, J. Pearson, S. Chambers
  Journal of Breath Research 01/2011; 5:046002.
• Article: Extra-oral halitosis: an overview.

  A Tangerman, E G Winkel
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  ABSTRACT: Halitosis can be subdivided into intra-oral and extra-oral halitosis, depending on the place where it originates. Most reports now agree that the most frequent sources of halitosis exist within the oral cavity and include bacterial reservoirs such as the dorsum of the tongue, saliva and periodontal pockets, where anaerobic bacteria degrade sulfur-containing amino acids to produce the foul smelling volatile sulfur compounds (VSCs), especially hydrogen sulfide (H(2)S) and methyl mercaptan (CH(3)SH). Tongue coating is considered to be the most important source of VSCs. Oral malodor can now be treated effectively. Special attention in this overview is given to extra-oral halitosis. Extra-oral halitosis can be subdivided into non-blood-borne halitosis, such as halitosis from the upper respiratory tract including the nose and from the lower respiratory tract, and blood-borne halitosis. The majority of patients with extra-oral halitosis have blood-borne halitosis. Blood-borne halitosis is also frequently caused by odorous VSCs, in particular dimethyl sulfide (CH(3)SCH(3)). Extra-oral halitosis, covering about 5-10% of all cases of halitosis, might be a manifestation of a serious disease for which treatment is much more complicated than for intra-oral halitosis. It is therefore of utmost importance to differentiate between intra-oral and extra-oral halitosis. Differences between intra-oral and extra-oral halitosis are discussed extensively. The importance of applying odor characterization of various odorants in halitosis research is also highlighted in this article. The use of the odor index, odor threshold values and simulation of bad breath samples is explained.
  Journal of Breath Research 03/2010; 4(1):017003.
• Article: Relationship between the β-galactosidase activity in saliva and parameters associated with oral malodor.

  M Yoneda, Y Masuo, N Suzuki, T Iwamoto, T Hirofuji
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  ABSTRACT: Volatile sulfur compounds (VSCs) are produced by enzymes capable of transforming S-amino acids to corresponding sulfides. Protein degradation by periodontopathogens plays an important role in this process, and the proteolysis of glycoproteins depends on the initial removal of the carbohydrate side chains. In the present report, we tested the relationship between the β-galactosidase activity in saliva and parameters that influence oral malodor, including daily habits and oral conditions. The prevalence of periodontopathic bacteria was also examined. Forty-nine saliva samples were collected from halitosis patients. Patients were examined for breath odor and other associated parameters. Their breath odor was assessed using an organoleptic test, a portable sulfide monitor and gas chromatography. The presence of periodontopathic bacteria in the saliva was also examined. β-galactosidase activity was measured with the chromogenic substrates 5-bromo-4-chloro-3-indoyl-β-d-galactopyranoside and isopropyl-β-d-thiogalactopyranoside. β-galactosidase activity was positively correlated with malodor strength (organoleptic score, portable sulfide monitor score and VSC concentrations). Enzyme activity was also correlated with the degree of observable tongue coating. However, it showed no relationship with periodontal condition, saliva flow, tooth decay, unfitted restorations or the color of any tongue coating. While there was no relationship with Porphyromonas gingivalis and Treponema denticola, there was a negative correlation with Prevotella intermedia. These results indicate that β-galactosidase activity plays an important role in malodor production. Interestingly, the activity of this enzyme was not related to the presence of periodontopathic bacteria, which are the main malodor-producing organisms. The results obtained here may have been associated with physiologic halitosis, which is not necessarily associated with oral problems or with periodontopathic bacteria.
  Journal of Breath Research 03/2010; 4(1):017108.
• Article: Modelling the effects of pH on tongue biofilm using a sorbarod biofilm perfusion system.

  Benjamin Taylor, John Greenman
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  ABSTRACT: The pH of the tongue biofilm is likely to influence microbial composition and ecology with consequent effects on the metabolic activities and generation of volatile sulfur compounds (VSC) and other malodour gasses. The aim of this study was to identify the effects of pH on the development of biofilms and hydrogen sulfide production using an in vitro tongue-derived biofilm model. Community level physiological profiling (CLPP) was employed to examine the influence of pH on the collective metabolic fingerprint of each tongue-derived biofilm. A sorbarod perfusion system (n = 6 sorbarods) was inoculated from a single suspension of tongue scrape sample and mixed community tongue-derived biofilms were grown at pH 5.5, 6.0, 6.5, 7.0 7.5 and 8.0. Biofilms were perfused with medium for 120 h and gas phase samples (n = 4 per biofilm) removed and analysed with a portable sulfide gas chromatograph before being sacrificed into 10 ml sterile PBS-diluent and cells suspended by vortex mixing. Further ten-fold dilutions were made (down to 10(-7)) and dilutions plated out onto selective (fastidious anaerobic agar (FAA) + 0.0025% vancomycin) and non-selective (FAA) media for enumeration of strict and facultative anaerobes respectively. Biofilm suspensions were also mixed with Biolog inoculation fluid and distributed into 96 wells of Biolog AN plates for CLPP. Tongue biofilms developed at pH 7.5 produced significant (p < 0.05) concentrations of H(2)S (≈52.2 ± SEM 5.6 µg H(2)S per ml biofilm gas phase) followed by tongue biofilm developed at pH 7.0 and 8.0 (≈43.2 ± SEM 3.5 and ≈ 39.6 ± SEM 7.3 µg H(2)S per ml biofilm gas phase respectively). Tongue biofilm developed at pH 6.0 and 6.5 produced approximately 21.5 ± SEM 2.3 and 37.1 ± SEM 1.7 µg H(2)S per ml biofilm gas phase respectively and tongue biofilm developed at pH 5.5 produced approximately 0.19 ± SEM 0.09 µg H(2)S per ml biofilm gas phase. Highest numbers of strict and facultative anaerobes were recovered from biofilms at pH 6.5 (1.10 × 10(12) and 2.07 × 10(12) cfu ml(-1) respectively), with a reduced number recovered from pH values above and below this range. CLPP and similarity index revealed biofilms at pH 6.5 and 7.0 most similar (S(j) = 78%) and most diverse in terms of metabolic activity. The biofilm at pH 5.5 was the least related to all others and least diverse. The sorbarod perfusion system, in conjunction with H(2)S analysis and CLPP, enables some of the physiological and ecological effects of pH at a local level within the biofilm on H(2)S production to be identified.
  Journal of Breath Research 03/2010; 4(1):017107.
• Article: Dispersal kinetics of deuterated water in the lungs and airways following mouth inhalation: real-time breath analysis by flowing afterglow mass spectrometry (FA-MS).

  Boon K Tan, David Smith, Patrik Spanel, Simon J Davies
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  ABSTRACT: Pulmonary oedema is a medical condition characterized by abnormal accumulation of fluid in the extravascular space in the alveoli. Effective oxygenation is impaired and this leads to significant short- and long-term morbidity and mortality. The detection and monitoring of pulmonary oedema by measuring lung water volume is therefore crucial in the initiation and guidance of therapeutic intervention. The current gold standard bedside measurement of extravascular lung water volume (EVLW) is the dilution method using various indicators, but despite the good correlation of the results with those obtained using the post-mortem gravimetric method, the invasiveness of the dilution technique limits its general application in the wider clinical setting. In the present preliminary experiments, the dispersal kinetics of deuterium (actually HDO) in exhaled breath of three healthy participants following the inhalation of deuterium oxide (D(2)O) vapour are explored as monitored using flowing afterglow mass spectrometry (FA-MS). Here, we present the basic ideas of lung water estimation using this novel technique, and briefly discuss its limitations and required future work.
  Journal of Breath Research 03/2010; 4(1):017109.
• Article: Comparison of breath and in-mouth collection for the measurement of oral malodorous compounds by gas chromatography using sulfur chemiluminescence detection.

  Debbie J Paetznick, G A Reineccius, T L Peppard, J M Herkert, P Lenton
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  ABSTRACT: Volatile sulfur compounds (VSCs), specifically hydrogen sulfide, methyl mercaptan and dimethyl sulfide, are generally considered to be the primary volatiles responsible for 'morning' malodors in breath. To date, the 'gold standard' for detecting VSC concentrations in breath is the use of gas chromatography coupled with sulfur chemiluminescence detection. Breath gas is often collected in a polypropylene syringe and then aliquots are injected into a gas chromatograph for analysis. The objective of this work was to compare the Twister™ bar in-mouth extraction methodology for measurement of VSCs with the gas syringe breath-sampling collection technique. The Twister bar technology captures malodorous compounds in the mouth as opposed to breath gas. Using these techniques, comparable results were obtained in studies demonstrating the efficacy of a proprietary oral malodor counteraction system.
  Journal of Breath Research 02/2010; 4(1):017106.
• Article: LC-ESI-MS/MS method for oxidative stress multimarker screening in the exhaled breath condensate of asbestosis/silicosis patients.

  K Syslová, P Kačer, M Kuzma, A Pankrácová, Z Fenclová, S Vlčková, J Lebedová, D Pelclová
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  ABSTRACT: The sensitive assay method was developed for a parallel, rapid and precise determination of the most prominent oxidative stress biomarkers: 8-iso-prostaglandin F(2α) a lipid oxidation biomarker, o-tyrosine an amino acid oxidation biomarker and 8-hydroxy-2'-deoxy-guanosine a nucleic acid oxidation biomarker. The method consisted of a pre-treatment part, freeze drying (lyophilization), serving the purpose of biomarkers concentration from the exhaled breath condensate and detection method LC-ESI-MS/MS, where the selected reaction-monitoring mode was used for its extremely high degree of selectivity and the stable-isotope-dilution assay for its high precision of quantification. The developed method is characterized by the following parameters: the precision was higher than 84.3% and the mean accuracy (relative error) was determined lower than 11.6%. The method was tested on samples obtained from patients diagnosed with asbestosis and silicosis, occupational diseases induced by oxidative stress, and then compared with samples from healthy subjects. The difference in biomarkers' concentration levels found between the two groups was statistically significant.
  Journal of Breath Research 01/2010; 4(1):017104.
• Article: Exhaled breath condensate: lessons learned from veterinary medicine.

  Petra Reinhold, Henri Knobloch
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  ABSTRACT: Exhaled breath condensate (EBC) describes any sample collected by cooling exhaled breath. Because the method of condensate collection is simple, non-invasive, repeatable and does not necessarily require patient cooperation, EBC is not only an interesting, but also challenging, biological sample. Despite a period of EBC research lasting for more than 15 years, there are still many open questions with respect to EBC collection and analysis, and many biomarkers are still awaiting careful validation. In veterinary research, EBC collection has been described in conscious animals including calves, pigs, horses, cats and dogs. Numerous studies performed in these domestic animals not only contributed substantially to the current knowledge about the potentials of EBC-based diagnoses but also demonstrated pitfalls in EBC collection, analysis and interpretation. This review summarizes information about the collection of EBC and the interpretation of EBC results, particularly with respect to proteins, leukotrienes, hydrogen peroxide, urea, ammonia and pH. Published data emphasize the need to standardize approaches to produce reproducible EBC data. Quantifying the concentration of the EBC component of interest exhaled in a defined volume of exhaled breath (instead of comparing concentrations of this component analysed in liquid EBC) is an important step of standardization that might help to overcome methodological limitations deriving from the EBC collection process. Although information is based on domestic animal studies, it contributes to the general understanding in EBC research-independent of any particular mammalian species-and opens new perspectives for further studies.
  Journal of Breath Research 12/2009; 4(1):017001.
• Article: Single time point diagnostic breath tests: a review.

  Anil S Modak
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  ABSTRACT: The metabolism of ingested xenobiotics is clinically significant to minimize risk and optimize therapeutic benefits. A majority of the drugs approved by the FDA are metabolized by phase I enzymes. Stable isotope-labeled xenobiotics can be used to provide rapid in vivo phenotype assessment of phase I enzymes. In this paper, we describe three simple, noninvasive phenotype breath tests using [(13)C]-dextromethorphan and [(13)C]-pantoprazole for assessing polymorphic CYP2D6 and CYP2C19 enzyme activity and [(13)C]-uracil to assess the enzyme activity of DPD, DPHD and β-ureidopropionase for identifying pyrimidine metabolic disorder. The results of the [(13)C]-dextromethorphan, [(13)C]-pantoprazole and [(13)C]-uracil breath test studies suggest that they have great potential for evaluating CYP2D6, CYP2C19 and DPD enzyme activities in a relatively short time with a single time point breath collection in a clinic or hospital setting. This would enable physicians to prescribe personalized therapy for each individual by selecting the ideal medication at the right dose for optimal efficacy of xenobiotics metabolized by these enzymes.
  Journal of Breath Research 12/2009; 4(1):017002.
• Article: Efficacy of a new mouthrinse formulation on the reduction of oral malodour in vivo. A randomized, double-blind, placebo-controlled, 3 week clinical study.

  W Wigger-Alberti, K Gysen, E-M Axmann, K-P Wilhelm
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  ABSTRACT: The present study was conducted to assess the efficacy of a new mouthrinse formulation in reducing oral malodour compared to that of commercially available products containing chlorhexidine (CHX) and a negative control. 174 healthy volunteers, each with an organoleptic score of at least 2 and an H(2)S level as part of the volatile sulfur compounds (VSC) higher than 50 ppb, were divided into four groups. Participants were stratified according to their organoleptic ratings (OR). Group I: mouthrinse I (250 ppm F(-) from amine fluoride/stannous fluoride (ASF), 0.2% zinc lactate, oral malodour counteractives); group II: mouthrinse II (0.05% CHX, 0.05% cetylpyridinium chloride, 0.14% zinc lactate); group III: mouthrinse III (0.12% CHX); group IV: tap water. All groups were instructed to perform standardized oral hygiene measures and to apply the respective test rinse twice daily after tooth brushing. Malodour was assessed by organoleptic measurement and by VSC levels at baseline, day 1, day 7, day 14 and day 21 into the study. To evaluate discolouration of the teeth, the colour was assessed at baseline and final visit. The ASF mouthrinse showed superior efficacy as compared to the negative control. A significant reduction in OR and VSC readings was achieved after single application as well as after 7 and 21 days of continuous use. Between test groups I-III no statistically significant differences were found at any time point. There was also a trend towards fewer side effects caused by the ASF product compared to the products containing CHX. The newly developed mouthrinse product significantly reduces oral malodour in patients with increased values both in OR and in VSC.
  Journal of Breath Research 12/2009; 4(1):017102.
• Article: Investigations into the micro-ecology of oral malodour in man and companion animals.

  R P Allaker
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  ABSTRACT: The loads and locations of bacterial types associated with oral malodour on the tongue surface and gingival crevice were investigated in man and the dog respectively. In the human study, samples were taken from 50 subjects with brushes at the dorsal anterior, dorsal middle, dorsal posterior, dorsal posterior to the circumvallate papillae (DPCP), lateral posterior and ventral posterior (VP) surfaces, and cultured appropriately. Malodour was assessed by trained judges. Mean volatile sulfur compound (VSC) producing bacterial counts (colony forming units/brush × 10(5)) were found to be highest (88.94) and lowest (0.33) at the DPCP and VP sites respectively. Anaerobic, gram-negative and VSC counts at DPCP surfaces increased with malodour intensity, whereas aerobic and S. salivarius counts decreased. The prevalence and populations of the VSC producing Porphyromonas and Prevotella species were determined in the dental plaque from 34 dogs. Porphyromonas gulae and Prevotella intermedia were present in 68% and 44% of dogs, and 47% and 23% of plaque samples respectively. P. gulae and Prev. intermedia counts increased with plaque quantity (P < 0.05) and gingivitis (P < 0.1). The close association observed between canine periodontal disease and measurements of oral malodour is supported.
  Journal of Breath Research 12/2009; 4(1):017103.
• Article: Changes in oxidative stress during outpatient surgery.

  Robert H Brown, Terence H Risby
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  ABSTRACT: Reactive oxygen species are associated with tissue inflammation and injury. Our laboratory has demonstrated that ethane, a stable product of lipid peroxidation, in exhaled breath can be used to measure total body oxidative stress. Herein patients were studied who underwent outpatient surgery, laproscopic bilateral tubal ligation (BTL, n = 10) and anterior cruciate ligament (ACL, n = 10) repair of the knee. These surgical procedures were expected to involve mild degrees of ischemia and reperfusion. In each of these cases propofol, an intravenous anesthetic with antioxidant properties, was used. Breath ethane was measured as a biomarker of oxidative stress that occurred at reperfusion of ischemic tissue. Data were analyzed by one-way analysis of variance. Clinically relevant concentrations of propofol were unable to completely block the increase in oxidative stress following reperfusion in either of these minor surgeries. Breath ethane increased significantly after reperfusion in both the BTL (p = 0.03) and the ACL (p = 0.005) patients. Also, the increase in oxidative stress was related to the time of ischemia.
  Journal of Breath Research 03/2009; 3(1):016002.
• Article: Propofol and in vivo oxidative stress: effects of preservative.

  Robert H Brown, Elizabeth M Wagner, Keary A Cope, Terence H Risby
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  ABSTRACT: Reactive oxygen species are associated with tissue inflammation and injury. Our laboratory has demonstrated that ethane, a stable product of lipid peroxidation, in exhaled breath can be used to measure total body oxidative stress. An ischemia-reperfusion model of lung injury in sheep has been studied in which pulmonary and bronchial lung perfusion could be interrupted and restored. The goal of this study was to investigate whether two commercial formulations of propofol and the individual components of the commercial formulations attenuated the oxidative stress produced in this model. Breath ethane and breath carbon monoxide were measured as biomarkers of oxidative stress that occur at reperfusion of ischemic tissue. Data were analyzed by a standard least-squares-fit model. One of the formulations for propofol, which contained the preservative ethylenediaminetetraacetic acid (EDTA), was found to decrease the overall level of oxidative stress in sheep. Furthermore, while several models of severe lung injury demonstrate additional production of reactive oxygen species, our model of ischemia/reperfusion of lung tissue did not.
  Journal of Breath Research 03/2009; 3(1):016003.
• Article: Exhaled breath condensate-site and mechanisms of formation.

  Eva Bondesson, Lennart T Jansson, Thomas Bengtsson, Per Wollmer
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  ABSTRACT: Exhaled breath condensate (EBC) analysis is a promising tool for diagnosis and management of pulmonary diseases. Its clinical usefulness is still limited however due to unresolved issues around e.g. reproducibility, anatomical site of origin of EBC solutes and mechanisms of EBC formation. To gain some knowledge on these issues, three different airway deposition patterns of an aqueous aerosol containing technetium-99m were studied in eight healthy non-smoking subjects. EBC was collected 20 min after each radioaerosol administration and analyzed for gamma radiation and electrolytes. Radioaerosol deposition in preferentially central lung compared with preferentially peripheral lung resulted in 3.8 times higher EBC radioactivity. EBC concentrations of Na(+) and K(+) correlated significantly indicating dilution by water vapor to be a major source of variability. Since Na(+)/K(+)- and Na(+)/S(2-)-concentration ratios, but not Na(+)/Cl(-)- or Na(+)/Ca(2+)-, were comparable to those previously reported for alveolar lining fluid (ALF), some mechanisms other than dilution are likely also to be involved. In conclusion, our findings indicate that EBC derives mainly from the central airways, that the electrolyte composition of EBC does not consistently reflect that of ALF, and that EBC concentrations of electrolytes are determined not only by ALF dilution with water vapor but also by other mechanisms.
  Journal of Breath Research 03/2009; 3(1):016005.
• Article: 3-Heptanone as a potential new marker for valproic acid therapy.

  S Erhart, A Amann, E Haberlandt, G Edlinger, A Schmid, W Filipiak, K Schwarz, P Mochalski, K Rostasy, D Karall, S Scholl-Bürgi
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  ABSTRACT: Breath gas samples from 27 patients with epilepsy (17 male and 10 female patients; mean age: 9.7 years, median age: 8.2 years, SD: ±4.2 years) were screened via proton transfer reaction mass spectrometry. The patients were treated with valproic acid (VPA) therapy, and blood samples for determination of VPA concentrations were surveyed. All patients showed significantly elevated concentrations of 3-heptanone (C(7)H(14)O) in exhaled breath gas (mean: 14.7 ppb, median: 13.8 ppb SD: ±5.7 ppb). In human breath, several hundred different volatile organic compounds can be detected. In breath of patients with valproic acid monotherapy, an increased concentration of 3-heptanone was measured. The objective of this study was to investigate if serum VPA concentrations correlate with 3-heptanone concentrations in exhaled breath. In conclusion, 3-heptanone in breath gas is significantly elevated in patients treated with the valproic acid, but does not correlate significantly with the VPA concentrations in serum or the daily dose of this drug.
  Journal of Breath Research 03/2009; 3(1):016004.
• Article: In vitro SIFT-MS validation of a breath fractionating device using a model VOC and ventilation system.

  Matthew J Seeley, Wan-Ping Hu, Jennifer M Scotter, Malina K Storer, Geoffrey M Shaw
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  ABSTRACT: The measurement of volatile organic compounds in exhaled breath is becoming recognized as a method of disease diagnosis and therapeutic monitoring. The aim of this study was to validate the collection of breath from intubated patients in the intensive care setting. This was done by assembling a system of ventilators and humidification to emulate the human respiratory system. A known concentration of acetone was spiked into the system to simulate alveolar and dead-space 'breath'. Selected-ion flow tube mass spectrometry (SIFT-MS) was used to directly measure gas at two separate points (headspace, distal circuit end) and from Tedlar bags collected using a remote breath fractionator. The mean acetone concentration for headspace, distal circuit end and Tedlar bag concentrations were calculated. The fractionator was effective in separating the early (dead space) and late phases of exhaled breath. Results from the late Tedlar bag samples collected by the remote breath fractionator showed a clear correlation with headspace and distal circuit end acetone concentrations. The collection for remote analysis of breath samples from immobile patients is made possible using the breath fractionator in conjunction with SIFT-MS analysis.
  Journal of Breath Research 03/2009; 3(1):016001.
• Article: β-Galactosidase activity and H(2)S production in an experimental oral biofilm.

  N Sterer, M Shaharabany, M Rosenberg
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  ABSTRACT: We recently suggested that oral malodor production involves two steps: (i) deglycosylation of glycoproteins and (ii) proteolysis and amino acid utilization of the protein core to yield volatiles such as volatile sulfide compounds (VSCs). Our aim was to test the hypothesis that β-galactosidase activity and VSC production occur in distinct areas of the biofilm by two different bacterial populations. Biofilms were grown anaerobically for seven days with or without antibiotics (i.e. vancomycin and metronidazole). Biofilms were stained for β-galactosidase activity and VSC production and studied using confocal laser scanning microscopy. Results showed that β-galactosidase activity occurs in the outer layers and disappears following vancomycin addition, whereas VSC production occurs deeper within the biofilm and disappears following metronidazole application. These findings suggest that β-galactosidase activity is produced mainly by Gram-positive oral bacteria at the outer portion of the biofilm, and VSC production occurs in the deeper layers by Gram-negative oral bacteria.
  Journal of Breath Research 03/2009; 3(1):016006.
• Article: The analysis of healthy volunteers' exhaled breath by the use of solid-phase microextraction and GC-MS.

  T Ligor, M Ligor, A Amann, C Ager, M Bachler, A Dzien, B Buszewski
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  ABSTRACT: We analysed breath and inhaled room air samples from 39 healthy volunteers (28 non-smokers, 8 smokers and 3 ex-smokers) by SPME-GC-MS. Mixed expiratory and indoor air samples were collected in freshly cleaned Tedlar bags. Eighteen millilitres of each sample were transferred into sealed, evacuated glass vials, preconcentrated by solid-phase microextraction (SPME, carboxen/polydimethylsiloxane) and investigated by gas chromatography with mass spectrometric detection (GC-MS). For the unequivocal identification of potential marker compounds, pure calibration mixtures of reference compounds (depending on commercial availability) were prepared to determine the retention time and mass spectra with respect to our analytical setting. Applying the adapted SPME-GC/MS method with limit of detection in the high ppb range (0.05-15.00 ppb), we succeeded in identifying altogether 38 compounds with concentrations in exhaled breath being at least 50% higher than concentration in inhaled air. From these 38 compounds, 31 were identified not only by the spectral library match but also by retention time of standards. A comparison of retention times and spectrum obtained for standards and determined compounds was performed. We found hydrocarbons (isoprene, 2-pentene, 2-methyl-1-pentene, benzene, toluene, p-cymene, limonene, 2,4-dimethylheptane, n-butane), ketones (acetone, hydroxypropanone, methylvinyl ketone), ethers (dimethyl ether, 1,3-dioxolane), esters (ethyl acetate), aldehydes (propanal, hexanal, heptanal, acrolein) and alcohols (ethanol, 2-metoxyethanol, isopropyl alcohol, 2,2,3,3- tetramethylcyclopropanemethanol, 3,4-dimethylcyclohexanol). Proper identification of compounds in different cohorts of patients and volunteers is the base for further investigation of origin, biochemical background and distribution of potential breath biomarkers.
  Journal of Breath Research 12/2008; 2(4):046006.