Tedlar Bags Research Articles

Measurement of trace gases and organic compounds in the smoke plume from a wildfire in Penedono (central Portugal)

Abstract Gas and particulate fractions were measured simultaneously from a wildfire in Penedono, central Portugal, which occurred in summer 2009. The total volatile hydrocarbons (THC) and carbon oxides (CO 2 and CO) collected in Tedlar bags were measured using automatic analysers with flame ionisation and non-dispersive infrared detectors, respectively. Carbonyls (formaldehyde and acetaldehyde) were sampled from the Tedlar bags in DNHP cartridges and analysed by high-performance liquid chromatography. Fine (PM 2.5 ) and coarse (PM 2.5-10 ) smoke particles were collected sequentially, on pre-fired quartz fibre filters, with a portable high-volume sampler. The detailed speciation of organic compounds in smoke samples was carried out by gas chromatography-mass spectrometry. The organic and elemental carbon content of particulate matter was analysed by a thermal-optical transmission technique. Average emission factors of 1.86 ± 0.80 and 0.063 ± 0.066 g kg −1 (dry basis) were obtained for acetaldehyde and formaldehyde, respectively. The THC, CO, CO 2 , PM 2.5 , PM 10 , OC and EC emission factors (g kg −1 fuel burned, dry basis) were 260 ± 88, 268 ± 92, 1200 ± 172, 37 ± 12.2, 40 ± 12.6, 21 ± 6.7 and 0.44 ± 0.21, respectively. The chromatographically resolved organics included n -alkanes, n -alkenes, n -alkanoic acids, n -di-acids, unsaturated fatty acids, phenolic compounds, ketones, steroids, di- and triterpenoids, PAHs, with retene as the major compound, oxygenated PAH and anhydrosugars.

Source apportionment of benzene downwind of a major point source

In the United States, the Emergency Planning and Community Right–to–Know Act requires sources that emit more than their Threshold Planning Quantity (TPQ) must publically report their total annual emissions. Because these values are aggregated over an entire year, high total emissions are often reported in the toxic release inventory. The Akwesasne Mohawk Reservation in rural Northern New York State lies downwind of an industrial source that reported annual benzene emissions of approximately 29 000 pounds. To assess if these emissions contributed significantly to the ambient concentrations, 24 hour canister samples were collected every 6th day from May 30 2007 to July 12 2008 at 9 locations on the Reservation. The samples were analyzed for benzene, toluene, ethyl benzene, and xylenes (BTEX) by GC/FID/MS using EPA Method TO15 procedures. In addition, gasoline samples (6 regular unleaded, 2 midgrade unleaded and 2 super unleaded) were collected in December 2007, May 2008 and July 2008 from five gas stations. The concentrations of BTEX in each gasoline sample were determined by headspace analysis. Vehicle tailpipe sampling was conducted by directly collecting samples from the tailpipe into Tedlar bags on 5 days: March 26, 2008, April 24, 2008, May 8, 2008, May 29, 2008 and June 12, 2008. Three samples were collected from each of the 22 vehicles that were fueled with unleaded regular gasoline from the reservation. Using these measured source profiles and ambient concentrations, the Chemical Mass Balance model was applied to each sample to assess the source contributions of BTEX. The results show that the predominant benzene source is vehicular exhaust with a small contribution from gasoline volatilization. The industrial plant has little or no impact on the ambient benzene concentrations in this community.

Influence of age and sex in exhaled breath samples investigated by means of infrared laser absorption spectroscopy

Breath gas analysis provides insight into human metabolism of healthy and ill individuals. As an innovative and non-invasive method, it opens up options to improve diagnostics, monitoring and treatment decisions. Mid-infrared laser absorption spectroscopy is utilized to detect CH4, H2O, CO2, NH3 and CH3OH in exhaled human breath. An off-line approach using breath sampling by means of Tedlar bags is applied. The breath gas samples are measured within the population-based epidemiological Study of Health in Pomerania (SHIP-TREND) performed at the University of Greifswald. The study covers about 5000 adult subjects aged 20–79 years within 3 years. Besides breath gas analysis many other examinations are conducted. It is expected to find associations between distinct concentration levels of species in the exhaled breath and diseases assessed in this study. The study will establish reference values for exhaled breath components and serve as background population for case-control studies. In the long run, morbidity and mortality follow-ups will be conducted, which will answer the question whether end-expiratory breath gas components predict future diseases and death. As first results, we present data from 45 dialysis patients (23 males, 22 females) which were recruited in a preliminary study in preparation for SHIP-TREND.

Comparison of Gas Sampling Bags to Temporarily Store Hydrogen Sulfide, Ammonia, and Greenhouse Gases

The National Air Emission Monitoring Study (NAEMS) project measured gas concentrations using automated semi-continuous gas analyzers. An alternative gas sampling technique is to use portable systems to fill 50 L gas sample bags over 24 h sampling periods and measure gas concentrations later in the laboratory. For this technique, a gas sampling bag that can retain gases over 24 h is needed. The objective of the study was to assess the impact of initial gas concentrations (low, medium, and high) and storage times (2, 6, 12, 24, 36, 48 h) on hydrogen sulfide, total reduced sulfur (TRS), ammonia, methane, and nitrous oxide stability in Tedlar and FlexFoil bags. Average gas concentrations ranged from 771 to 2,655 ppb, from 782 to 2,750 ppb, from 657 to 1,997 ppb, from 10,441 to 13,803 ppb, and from 337 to 344 ppb for H2S, TRS, NH3, CH4, and N2O, respectively. Bag reusability and background contamination were also investigated. Percent recoveries from FlexFoil bags ranged from 75% to 99.5% for all gases and concentrations except for TRS at high concentrations. For TRS at high concentrations, percent recovery from FlexFoil bags was 68.8%. No gas desorption or permeation was observed when using new FlexFoil bags. FlexFoil bags were more durable than Tedlar bags to mechanical stress and aging effects. There was no need to use a cover for FlexFoil bags to protect samples from sunlight. The cost of FlexFoil bags was lower than that of Tedlar bags.

Some Insights into Analytical Bias Involved in the Application of Grab Sampling for Volatile Organic Compounds: A Case Study against Used Tedlar Bags

In this study, we have examined the patterns of VOCs released from used Tedlar bags that were once used for the collection under strong source activities. In this way, we attempted to account for the possible bias associated with the repetitive use of Tedlar bags. To this end, we selected the bags that were never heated. All of these target bags were used in ambient temperature (typically at or below 30°C). These bags were also dealt carefully to avoid any mechanical abrasion. This study will provide the essential information regarding the interaction between VOCs and Tedlar bag materials as a potential source of bias in bag sampling approaches.

Breath ammonia and trimethylamine allow real-time monitoring of haemodialysis efficacy

Non-invasive monitoring of breath ammonia and trimethylamine using Selected-ion-flow-tube mass spectroscopy (SIFT-MS) could provide a real-time alternative to current invasive techniques. Breath ammonia and trimethylamine were monitored by SIFT-MS before, during and after haemodialysis in 20 patients. In 15 patients (41 sessions), breath was collected hourly into Tedlar bags and analysed immediately (group A). During multiple dialyses over 8 days, five patients breathed directly into the SIFT-MS analyser every 30 min (group B). Pre- and post-dialysis direct breath concentrations were compared with urea reduction, Kt/V and creatinine concentrations. Dialysis decreased breath ammonia, but a transient increase occurred mid treatment in some patients. Trimethylamine decreased more rapidly than reported previously. Pre-dialysis breath ammonia correlated with pre-dialysis urea in group B (r2 = 0.71) and with change in urea (group A, r2 = 0.24; group B, r2 = 0.74). In group B, ammonia correlated with change in creatinine (r2 = 0.35), weight (r2 = 0.52) and Kt/V (r2 = 0.30). The ammonia reduction ratio correlated with the urea reduction ratio (URR) (r2 = 0.42) and Kt/V (r2 = 0.38). Pre-dialysis trimethylamine correlated with Kt/V (r2 = 0.21), and the trimethylamine reduction ratio with URR (r2 = 0.49) and Kt/V (r2 = 0.36). Real-time breath analysis revealed previously unmeasurable differences in clearance kinetics of ammonia and trimethylamine. Breath ammonia is potentially useful in assessment of dialysis efficacy.

Summer 2009 wildfires in Portugal: Emission of trace gases and aerosol composition

Abstract In summer 2009, emissions of trace gases and aerosols from several wildfires occurring in Portugal were sampled. A portable high-volume sampler was used to collect sequentially, on quartz fibre filters, coarse (PM2.5–10) and fine (PM2.5) smoke particles. Tedlar air sampling bags have been used for complementary chemical characterisation of the gaseous phase. The carbonaceous content (elemental and organic carbon, EC/OC) of particulate matter was analysed by a thermal-optical transmission technique. The levels of almost 50 elements were quantified by inductively coupled plasma-mass spectrometry. The water-soluble ions were obtained by ion chromatography. Emission factors of species that are favoured by the smouldering phase (e.g. CO) were above the values reported in the literature for biomass burning in other ecosystems. The CO emission factors were 231 ± 117 g kg−1 biomass (dry basis) burned. Emissions of compounds that are promoted in fresh plumes and during the flaming phase, such as CO2, were generally lower than those proposed for savannah and tropical forest fires. The CO2 emission factors ranged from about 1000 to 1700 g kg−1. Total hydrocarbons, PM2.5, PM10 and OC presented variable emissions, but in general substantially higher than values reported for wildfires in African and Amazonian biomes. The emission factors obtained in Portugal were as follows (in g kg−1 biomass, dry basis): 6–350 for total hydrocarbons, 0.5–42 for PM2.5, 1–60 for PM10, and 0.2–42 for OC (in PM10). The organic carbon-to-elemental carbon ratios measured in the present study largely exceeded those obtained by other researchers. The aerosol mass was dominated by organic matter (OC/PM2.5 = 50 ± 18%, OC/PM2.5–10 = 36 ± 18%). The metal elements represented, on average, 1.23 and 0.91%, while the measured water-soluble ions accounted for 2.6 and 2.1% of the PM2.5 and PM2.5–10 mass, respectively. Carbonates accounted for 0.15–3.1% (average = 0.83%) of PM2.5–10. The dominant elements were B, Ti, Mn, Cu, Zn, Zr and Ba.

Electronic nose breathprints are independent of acute changes in airway caliber in asthma.

Molecular profiling of exhaled volatile organic compounds (VOC) by electronic nose technology provides breathprints that discriminate between patients with different inflammatory airway diseases, such as asthma and COPD. However, it is unknown whether this is determined by differences in airway caliber. We hypothesized that breathprints obtained by electronic nose are independent of acute changes in airway caliber in asthma. Ten patients with stable asthma underwent methacholine provocation (Visit 1) and sham challenge with isotonic saline (Visit 2). At Visit 1, exhaled air was repetitively collected pre-challenge, after reaching the provocative concentration (PC20) causing 20% fall in forced expiratory volume in 1 second (FEV1) and after subsequent salbutamol inhalation. At Visit 2, breath was collected pre-challenge, post-saline and post-salbutamol. At each occasion, an expiratory vital capacity was collected after 5 min of tidal breathing through an inspiratory VOC-filter in a Tedlar bag and sampled by electronic nose (Cyranose 320). Breathprints were analyzed with principal component analysis and individual factors were compared with mixed model analysis followed by pairwise comparisons. Inhalation of methacholine led to a 30.8 ± 3.3% fall in FEV1 and was followed by a significant change in breathprint (p = 0.04). Saline inhalation did not induce a significant change in FEV1, but altered the breathprint (p = 0.01). However, the breathprint obtained after the methacholine provocation was not significantly different from that after saline challenge (p = 0.27). The molecular profile of exhaled air in patients with asthma is altered by nebulized aerosols, but is not affected by acute changes in airway caliber. Our data demonstrate that breathprints by electronic nose are not confounded by the level of airway obstruction.

Assessment of Environmental Tobacco Smoke Contamination in Public Premises: Significance of 2,5-Dimethylfuran as an Effective Marker

Contamination by environmental tobacco smoke (ETS) on premises where smoking is permitted is evaluated. Although all target VOCs evaluated show significant differences between smoking and nonsmoking indoors, the results obtained indicate that 2,5-dimethylfuran is the most appropriate and effective marker of ETS contamination given that this compound is only detected in environments where people have smoked and so the detection of this compound cannot be attributed to other contamination sources such as traffic. Moreover, the air levels of this compound due to coffee aroma are below the detection limits for this methodology. A preliminary study is performed to evaluate whether 2,5-dimethylfuran, a smoking breath biomarker, can be detected in passive smokers working in smoking environments. The compound was continuously detected in the breath of nonsmoking employees after being in direct contact with ETS for just a few hours. The Tedlar gas sampling bags had 5% loss of 2,5-dimethylfuran after 3 h of storage, which we took as the maximum recommended period for air sample storage.

Suitability of Tedlar ® gas sampling bags for siloxane quantification in landfill gas

Landfill or digester gas can contain man-made volatile methylsiloxanes (VMS), usually in the range of a few milligrams per normal cubic metre (Nm 3). Until now, no standard method for siloxane quantification exists and there is controversy with respect to which sampling procedure is most suitable. This paper presents an analytical and a sampling procedure for the quantification of common VMS in biogas via GC–MS and polyvinyl fluoride (Tedlar ®) bags. Two commercially available Tedlar bag models are studied. One is equipped with a polypropylene valve with integrated septum, the other with a dual port fitting made from stainless steel. Siloxane recovery in landfill gas samples is investigated as a function of storage time, temperature, surface-to-volume ratio and background gas. Recovery was found to depend on the type of fitting employed. The siloxanes sampled in the bag with the polypropylene valve show high and stable recovery, even after more than 30 days. Sufficiently low detection limits below 10 μg Nm −3 and good reproducibility can be achieved. The method is therefore well applicable to biogas, greatly facilitating sampling in comparison with other common techniques involving siloxane enrichment using sorption media.

Application of GC-MS with a SPME and thermal desorption technique for determination of dimethylamine and trimethylamine in gaseous samples for medical diagnostic purposes

Biogenic amines are interesting compounds which may be of use for medical diagnosis or therapeutic monitoring. The present paper deals with the problems that occur with concentration determination of dimethylamine (DMA) and trimethylamine (TMA). These occur in the breath of people suffering from renal disease. The measurement of amines present in trace concentrations requires the application of suitable analytical methods during sampling, storage and preconcentration. This is particularly so due to their polar and basic properties. In this paper, the application of solid phase microextraction (SPME) and thermal desorption (TD) with subsequent measurement by GC-MS for the determination of amines is discussed. For DMA, preconcentration by SPME did not give satisfactory results. TMA may be analysed using SPME preconcentration with an LOD of 1.5 ppb. Thermal desorption with Tenax as the adsorbing material allows reliable concentration determination for TMA (LOD = 0.5 ppb) and DMA (LOD = 4.6 ppb). DMA cannot be stored reliably in Tedlar bags and longer storage on Tenax (with subsequent TD) does not give good repeatability of results. For TMA, storage can be done on Tenax or in bags, the best results for the latter being achieved with Flex Foil bags.

Effectiveness of a Manure Scraper System for Odor Control in Tunnel-Ventilated Swine Finisher Barns

Options for odor control from tunnel-ventilated swine barns are limited. Automated scrapers have proven successful for reducing odor at free-stall dairies and for reducing hydrogen sulfide at a research-scale swine facility, but their effectiveness for reducing odor in commercial tunnel-ventilated swine barns has never been evaluated. A research project was conducted to compare odor concentrations in exhaust of traditional flush barns and barns equipped with automated scrapers. The study was conducted at commercial tunnel-ventilated swine barns owned by Premium Standard Farms LLC in northwest Missouri. Odor samples were collected from the barn exhaust in Tedlar bags and analyzed by trained human panelists using triangular forced-choice olfactometry. Total reduced sulfur (TRS) concentrations were measured with a portable Jerome meter, and volatile organic compounds (VOCs) were sampled in sorbent tubes and analyzed by gas chromatography/mass spectrometry. Mean odor concentrations (dilutions to threshold, DT) were 75.6% lower in exhaust from scraper barns (DT = 941) than flush barns (DT = 3860) (p < 0.001). Mean recognition thresholds (RT) were 76.4% lower in exhaust from scraper barns (RT = 494) than flush barns (RT = 2095) (p < 0.001). TRS concentrations averaged 1.59 and 0.16 ppm in flush and scraper barns, respectively, for an 89.9% difference (p = 0.029). Hedonic tone and intensity were statistically similar for flush and scraper barns. Odor was positively correlated with TRS in flush barns, while in scraper barns odor was positively correlated with butyric acid, 4-ethylphenol, indole, and skatole. Odor concentrations were significantly greater during flush than between flush events (p = 0.002), but there was no difference in mean odor concentrations during scrape and between scrape events (p = 0.20). These results show that scraper barns are a practical alternative for the control of odor emitted from tunnel-ventilated swine barns.

Evaluation of a Field-Scale Surface Aeration System in an Anaerobic Poultry Lagoon

Odor from animal feeding operations (AFOs) is a leading public nuisance that livestock and poultry producers face frequently. The objective of this study was to evaluate a field-scale surface aeration system to minimize odor from an anaerobic poultry lagoon in Texas. The aeration module consisted of three aerators, each aerator contained two venturi air injectors arranged in parallel and connected to a perforated PVC pipe network that aerated a site of 23 m 23 m. The pipe network in the aeration system was placed 0.30 m below the liquid surface for aerating the lagoon. To compare the effect of aeration on lagoon odors and other parameters, a non-aerated (control) site was established about 30 m away from the aerated site to minimize treatment interference. Automatic samplers were used to collect effluent samples from each site at a depth of 0.30 m below the liquid surface once a week for 14 weeks. The samples were analyzed for changes in biochemical oxygen demand (BOD5), volatile fatty acids (VFAs), solids, and nutrients concentrations. Real-time dissolved oxygen and water temperature were also monitored by deploying sensors at the same depth. Six air samples (three each from aerated and non-aerated sites) were collected once a week in 10-L Tedlar bags and were analyzed for odors (dilution to threshold, DT), ammonia (NH3), and hydrogen sulfide (H2S) concentrations. Average DO and NH3 concentrations from aerated liquid were significantly (p<0.05) higher (62% and 27%, respectively) than the non-aerated liquid. On the other hand, DT value in the aerated site was significantly lower (50%) than the non-aerated site. Average H2S and BOD5 concentrations in the aerated site were about 16% and 13% lower, respectively, than the non-aerated site for the liquid and air samples collected three days after flushing, although these concentrations between the two sites were not significantly different (p>0.05). There were no significant differences in solids and nutrient concentrations between aerated and non-aerated site. These results demonstrated that surface aeration is effectively reducing odor and H2S concentrations and increasing NH3 concentrations in the aerated site as compared to the non-aerated. Struvite build-up in the lagoon liquid circulation pump, venturi injectors and the PVC pipe network, and clogging of strainers and PVC pipe aeration holes with lagoon surface scum and egg-shells required frequent cleaning and maintenance of the aeration system.

Noninvasive detection of lung cancer by analysis of exhaled breath

BackgroundLung cancer is one of the leading causes of death in Europe and the western world. At present, diagnosis of lung cancer very often happens late in the course of the disease since inexpensive, non-invasive and sufficiently sensitive and specific screening methods are not available. Even though the CT diagnostic methods are good, it must be assured that "screening benefit outweighs risk, across all individuals screened, not only those with lung cancer". An early non-invasive diagnosis of lung cancer would improve prognosis and enlarge treatment options. Analysis of exhaled breath would be an ideal diagnostic method, since it is non-invasive and totally painless.MethodsExhaled breath and inhaled room air samples were analyzed using proton transfer reaction mass spectrometry (PTR-MS) and solid phase microextraction with subsequent gas chromatography mass spectrometry (SPME-GCMS). For the PTR-MS measurements, 220 lung cancer patients and 441 healthy volunteers were recruited. For the GCMS measurements, we collected samples from 65 lung cancer patients and 31 healthy volunteers. Lung cancer patients were in different disease stages and under treatment with different regimes. Mixed expiratory and indoor air samples were collected in Tedlar bags, and either analyzed directly by PTR-MS or transferred to glass vials and analyzed by gas chromatography mass spectrometry (GCMS). Only those measurements of compounds were considered, which showed at least a 15% higher concentration in exhaled breath than in indoor air. Compounds related to smoking behavior such as acetonitrile and benzene were not used to differentiate between lung cancer patients and healthy volunteers.ResultsIsoprene, acetone and methanol are compounds appearing in everybody's exhaled breath. These three main compounds of exhaled breath show slightly lower concentrations in lung cancer patients as compared to healthy volunteers (p < 0.01 for isoprene and acetone, p = 0.011 for methanol; PTR-MS measurements). A comparison of the GCMS-results of 65 lung cancer patients with those of 31 healthy volunteers revealed differences in concentration for more than 50 compounds. Sensitivity for detection of lung cancer patients based on presence of (one of) 4 different compounds not arising in exhaled breath of healthy volunteers was 52% with a specificity of 100%. Using 15 (or 21) different compounds for distinction, sensitivity was 71% (80%) with a specificity of 100%. Potential marker compounds are alcohols, aldehydes, ketones and hydrocarbons.ConclusionGCMS-SPME is a relatively insensitive method. Hence compounds not appearing in exhaled breath of healthy volunteers may be below the limit of detection (LOD). PTR-MS, on the other hand, does not need preconcentration and gives much more reliable quantitative results then GCMS-SPME. The shortcoming of PTR-MS is that it cannot identify compounds with certainty. Hence SPME-GCMS and PTR-MS complement each other, each method having its particular advantages and disadvantages. Exhaled breath analysis is promising to become a future non-invasive lung cancer screening method. In order to proceed towards this goal, precise identification of compounds observed in exhaled breath of lung cancer patients is necessary. Comparison with compounds released from lung cancer cell cultures, and additional information on exhaled breath composition in other cancer forms will be important.

Exhaled Breath Profiling Enables Discrimination of Chronic Obstructive Pulmonary Disease and Asthma

Chronic obstructive pulmonary disease (COPD) and asthma can exhibit overlapping clinical features. Exhaled air contains volatile organic compounds (VOCs) that may qualify as noninvasive biomarkers. VOC profiles can be assessed using integrative analysis by electronic nose, resulting in exhaled molecular fingerprints (breathprints). We hypothesized that breathprints by electronic nose can discriminate patients with COPD and asthma. Ninety subjects participated in a cross-sectional study: 30 patients with COPD (age, 61.6 +/- 9.3 years; FEV(1), 1.72 +/- 0.69 L), 20 patients with asthma (age, 35.4 +/- 15.1 years; FEV(1) 3.32 +/- 0.86 L), 20 nonsmoking control subjects (age, 56.7 +/- 9.3 years; FEV(1), 3.44 +/- 0.76 L), and 20 smoking control subjects (age, 56.1 +/- 5.9 years; FEV(1), 3.58 +/- 0.78). After 5 minutes of tidal breathing through an inspiratory VOC filter, an expiratory vital capacity was collected in a Tedlar bag and sampled by electronic nose. Breathprints were analyzed by discriminant analysis on principal component reduction resulting in cross-validated accuracy values (accuracy). Repeatability and reproducibility were assessed by measuring samples in duplicate by two devices. Breathprints from patients with asthma were separated from patients with COPD (accuracy 96%; P < 0.001), from nonsmoking control subjects (accuracy, 95%; P < 0.001), and from smoking control subjects (accuracy, 92.5%; P < 0.001). Exhaled breath profiles of patients with COPD partially overlapped with those of asymptomatic smokers (accuracy, 66%; P = 0.006). Measurements were repeatable and reproducible. Molecular profiling of exhaled air can distinguish patients with COPD and asthma and control subjects. Our data demonstrate a potential of electronic noses in the differential diagnosis of obstructive airway diseases and in the risk assessment in asymptomatic smokers. Clinical trial registered with www.trialregister.nl (NTR 1282).

An electronic nose in the discrimination of breath from smokers and non-smokers: a model for toxin exposure

Exhaled breath contains hundreds of volatile organic compounds (VOCs) that may be used as non-invasive markers of lung disease. Electronic noses (e-noses) can analyse VOCs by composite nanosensor arrays with learning algorithms. This study investigated the use of an e-nose (Cyranose C320) to distinguish the breath of smokers from that of non-smokers. Smoking and non-smoking subjects exhaled from total lung capacity into a 2 L Tedlar bag and these samples were introduced offline to the e-nose in a random order. Two classes of breath, ‘smoker’ and ‘non-smoker’, were established and this model was then cross-validated. Principal component analysis then identified the maximal point of difference between classes. Smellprints of breath from smokers were separated from those of non-smokers (cross-validation value, 95%; Mahalanobis distance, 3.96). Subsequently, 15 smokers (mean age 37.9 ± 4.78 years, FEV1 3.15 ± 0.21 L), and 24 non-smokers (add mean age and FEV1 as for smokers) were sampled to revalidate the model. The e-nose correctly identified the smoking status in 37 of the 39 subjects. This demonstrates that the e-nose is simple to use in clinical practice and can differentiate the breath of smokers from that of non-smokers. It may prove to be a useful, non-invasive tool for further breath assessment of exposure to other inhaled noxious substances as well as disease monitoring.

Breath acetone—aspects of normal physiology related to age and gender as determined in a PTR-MS study

The present study was performed to determine the variations of breath acetone concentrations with age, gender and body-mass index (BMI). Previous investigations were based on a relatively small cohort of subjects (see Turner et al 2006 Physiol. Meas. 27 321–37). Since exhaled breath analysis is affected by considerable variation, larger studies are needed to get reliable information about the correlation of concentrations of volatiles in breath when compared with age, gender and BMI. Mixed expiratory exhaled breath was sampled using Tedlar bags. The concentrations of a mass-to-charge ratio (m/z) of 59, attributed to acetone, were then determined using proton transfer reaction-mass spectrometry. Our cohort, consisting of 243 adult volunteers not suffering from diabetes, was divided into two groups: one that fasted overnight prior to sampling (215 volunteers) and the other without a dietary control (28 volunteers). In addition, we considered a group of 44 healthy children (5–11 years old).The fasted subjects' concentrations of acetone ranged from 177 ppb to 2441 ppb, with an overall geometric mean (GM) of 628 ppb; in the group without a dietary control, the subjects' concentrations ranged from 281 ppb to 1246 ppb with an overall GM of 544 ppb. We found no statistically significant shift between the distributions of acetone levels in the breath of males and females in the fasted group (the Wilcoxon-Mann–Whitney test yielded p = 0.0923, the medians being 652 ppb and 587 ppb). Similarly, there did not seem to be a difference between the acetone levels of males and females in the group without a dietary control. Aging was associated with a slight increase of acetone in the fasted females; in males the increase was not statistically significant. Compared with the adults (a merged group), our group of children (5–11 years old) showed lower concentrations of acetone (p < 0.001), with a median of 263 ppb. No correlation was found between the acetone levels and BMI in adults. Our results extend those of Turner et al's (2006 Physiol. Meas. 27 321–37), who analyzed the breath of 30 volunteers (without a dietary control) by selected ion flow tube-mass spectrometry. They reported a positive correlation with age (but without statistical significance in their cohort, with p = 0.82 for males and p = 0.45 for females), and, unlike us, arrived at a p-value of 0.02 for the separation of males and females with respect to acetone concentrations. Our median acetone concentration for children (5–11 years) coincides with the median acetone concentration of young adults (17–19 years) reported by Spanel et al (2007 J. Breath Res. 1 026001).

Improved pre-concentration and detection methods for volatile sulphur breath constituents

Suitability of different types of pre-concentration (solid phase microextraction and sorbent trapping) and detection (flame photometric detector (FPD) and mass selective detector (MSD)) for gas chromatographic determination of sulphur-containing compounds (H 2S, MeSH, EtSH, DMS, COS and CS 2) in breath-gas was assessed in this study. Several factors like influence of humidity, influence of oxygen, or stability of target compounds in extraction vessels (SPME vials and sorbent tubes) were investigated. Despite poor stability of VSCs in SPME vials and matrix effects (unfavorable influence of humidity), SPME was found to be a fast and reliable enrichment method, which coupled with mass selective detector provided satisfactory LODs of target compounds at the ppt level (from 0.15 ppb for CS 2 to 2.3 ppb for H 2S). Application of sorbent trapping with two-bed sorbent tubes containing Tenax TA and Carboxen 1000 gave excellent LODs (0.03–0.3 ppb for 200 ml sample and MSD). Stability of investigated VSCs in sorbents was found to be very poor (30–40% losses after 2 h). FPD showed satisfactory sensitivity only when it was coupled with sorbent trapping. Breath samples were collected into Tedlar bags in a CO 2-controlled manner. Humidity was removed during sampling (permeation dryer – Nafion) to avoid unfavorable water dependent effects during analysis.

In vitro SIFT-MS validation of a breath fractionating device using a model VOC and ventilation system

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.

Detection of 2-Pentylfuran in the breath of patients withAspergillus fumigatus

Aspergillus fumigatus produces 2-pentylfuran (2-PF) when cultured on blood agar, nutrient agar and other media. As 2-PF is not known to be produced by mammalian metabolism we hypothesized that it is detectable in breath of patients colonized or infected with A. fumigatus. Breath was tested for 2-PF from normal subjects, those undergoing chemotherapy, and adults at risk of colonization or infection with A. fumigatus because of bronchiectasis, cystic fibrosis, or immune suppression. Breath samples were collected in five L tedlar bags and analyzed by Gas Chromatography/Mass Spectroscopy (GC/MS) in MS-MS mode. 2-PF was not detected in breath 14 healthy controls, in one of 10 neutropenic subjects and 16 of 32 patients with lung disease. The sensitivity and specificity of the 2-PF breath tests when compared with recurrent isolation of aspergillus from sputum or from bronchoalveolar lavage over two months was 77% and 78% respectively. As 2-PF is not normally found in human breath its presence may reflect the active metabolism of A. fumigatus in the airways and form the basis of a new diagnostic breath test for Aspergillus infection.