[Morisco2013] "Rapid "breath-print" of liver cirrhosis by proton transfer reaction time-of-flight mass spectrometry. A pilot study.",
, vol. 8, no. 4: Department of Clinical Medicine and Surgery, University of Naples Federico II, Naples, Italy. email@example.com, pp. e59658, 2013.
The aim of the present work was to test the potential of Proton Transfer Reaction Time-of-Flight Mass Spectrometry (PTR-ToF-MS) in the diagnosis of liver cirrhosis and the assessment of disease severity by direct analysis of exhaled breath. Twenty-six volunteers have been enrolled in this study: 12 patients (M/F 8/4, mean age 70.5 years, min-max 42-80 years) with liver cirrhosis of different etiologies and at different severity of disease and 14 healthy subjects (M/F 5/9, mean age 52.3 years, min-max 35-77 years). Real time breath analysis was performed on fasting subjects using a buffered end-tidal on-line sampler directly coupled to a PTR-ToF-MS. Twelve volatile organic compounds (VOCs) resulted significantly differently in cirrhotic patients (CP) compared to healthy controls (CTRL): four ketones (2-butanone, 2- or 3- pentanone, C8-ketone, C9-ketone), two terpenes (monoterpene, monoterpene related), four sulphur or nitrogen compounds (sulfoxide-compound, S-compound, NS-compound, N-compound) and two alcohols (heptadienol, methanol). Seven VOCs (2-butanone, C8-ketone, a monoterpene, 2,4-heptadienol and three compounds containing N, S or NS) resulted significantly differently in compensate cirrhotic patients (Child-Pugh A; CP-A) and decompensated cirrhotic subjects (Child-Pugh B+C; CP-B+C). ROC (Receiver Operating Characteristic) analysis was performed considering three contrast groups: CP vs CTRL, CP-A vs CTRL and CP-A vs CP-B+C. In these comparisons monoterpene and N-compound showed the best diagnostic performance.Breath analysis by PTR-ToF-MS was able to distinguish cirrhotic patients from healthy subjects and to discriminate those with well compensated liver disease from those at more advanced severity stage. A breath-print of liver cirrhosis was assessed for the first time.
[Avison2013] "Real-Time Flavor Analysis: Optimization of a Proton-Transfer-Mass Spectrometer and Comparison with an Atmospheric Pressure Chemical Ionization Mass Spectrometer with an MS-Nose Interface.",
J Agric Food Chem
, vol. -: Firmenich S.A., Rue de la BergÃ¨re 7, Meyrin 2, CH-1217 Geneva, Switzerland., pp. -, Feb, 2013.
Two techniques are recognized for the real-time analysis of flavors during eating and drinking, atmospheric pressure chemical ionization mass spectrometry (APCI-MS), and proton transfer reaction mass spectrometry (PTR-MS). APCI-MS was developed for the analysis of flavors and fragrances, whereas PTR-MS was originally developed and optimized for the analysis of atmospheric pollutants. Here, the suitability of the two techniques for real-time flavor analysis is compared, using a varied range of common flavor compounds. An Ionicon PTR-MS was first optimized and then its performance critically compared with that of APCI-MS. Performance was gauged using the capacity for soft ionization, dynamic linear range, and limit of detection. Optimization of the PTR-MS increased the average sensitivity by a factor of more than 3. However, even with this increase in sensitivity, the Limit of Detection was typically 10 times higher and the Dynamic Linear Range ten times narrower than that of the APCI-MS.
[Winkler2013] "Real-time metabolic monitoring with proton transfer reaction mass spectrometry",
Journal of breath research
, vol. 7, no. 3: IOP Publishing, pp. 036006, 2013.
<p><span style="color: rgb(0, 0, 0); font-family: Arial, Helvetica, Verdana, sans-serif; font-size: 12px; line-height: 16.1875px; background-color: rgb(255, 255, 255);">We analysed the time evolution of several volatile organic compounds formed by the catabolism of ingested isotope-labelled ethanol using real-time breath gas analysis with proton-transfer-reaction mass spectrometry. Isotope labelling allowed distinguishing the emerging volatile metabolites from their naturally occurring, highly abundant counterparts in the human breath. Due to an extremely low detection limit of the employed technologies in the parts per trillion per volume range, it was possible to detect the emerging metabolic products in exhaled breath within ~10 min after oral ingestion of isotope-labelled ethanol. We observed that ethanol was in part transformed into deuterated acetone and isoprene, reflecting the different fates of activated acetic acid (acetyl-coenzyme A), formed in ethanol metabolism. Using ethanol as a model clearly demonstrated the value of the here presented technique for the search for volatile markers for metabolic disorders in the exhaled breath and its potential usefulness in the diagnosis and monitoring of such diseases.</span></p>
 "Real-time monitoring of emissions from monoethanolamine-based industrial scale carbon capture facilities.",
Environ Sci Technol
, vol. 47, pp. 14306–14314, Dec, 2013.
<p>We demonstrate the capabilities and properties of using Proton Transfer Reaction time-of-flight mass spectrometry (PTR-ToF-MS) to real-time monitor gaseous emissions from industrial scale amine-based carbon capture processes. The benchmark monoethanolamine (MEA) was used as an example of amines needing to be monitored from carbon capture facilities, and to describe how the measurements may be influenced by potentially interfering species in CO2 absorber stack discharges. On the basis of known or expected emission compositions, we investigated the PTR-ToF-MS MEA response as a function of sample flow humidity, ammonia, and CO2 abundances, and show that all can exhibit interferences, thus making accurate amine measurements difficult. This warrants a proper sample pretreatment, and we show an example using a dilution with bottled zero air of 1:20 to 1:10 to monitor stack gas concentrations at the CO2 Technology Center Mongstad (TCM), Norway. Observed emissions included many expected chemical species, dominantly ammonia and acetaldehyde, but also two new species previously not reported but emitted in significant quantities. With respect to concerns regarding amine emissions, we show that accurate amine quantifications in the presence of water vapor, ammonia, and CO2 become feasible after proper sample dilution, thus making PTR-ToF-MS a viable technique to monitor future carbon capture facility emissions, without conventional laborious sample pretreatment.</p>
[Rodiera2013] "Real-time monitoring of end-tidal propofol in exhaled air: where we were, where we are, and where we would like to be. Preliminary results: 3AP2-3",
European Journal of Anaesthesiology (EJA)
, vol. 30: LWW, pp. 41–41, 2013.
Background and Goal of Study: There have been several studies published about the presence of propofol particles in exhaled air. However, it is not clear whether this technique can be reliable and reproducible as to have a clear impact on research or clinical practice. In the past years we have been working on improving the methodology and optimizing the results, improving sampling and data collection to increase the sensitivity and accuracy. A LabView (National Instruments) application developed allows the connection of the infusion pumps, vital signs monitor, BIS and PTR‐MS (QMS Ionicon High Sensitivity Proton Transfer Reaction Mass Spectrometer), which allows automatic real‐time data collection. We have now developed a new sampling cannula of low absorbent material (PEEK) which introduced into the oro‐tracheal tube allows taking the sample. Simultaneously, the sampling system has been improved by heating it and including a micro valve that allows air sampling, exclusively on the expiratory phase.Materials and Methods: 300 patients, 18‐60 years old both sexes ASA I II, scheduled for surgery under general anesthesia were involved. Vital signs, TCI parameters and the propofol concentration (178+1 amu), acetone (58+1 amu) and isoprene (68+1 amu) in expired air are recorded. Propofol concentrations in expired air are being compared with the plasmatic concentration and effect offered by the TCI, as well as its correlation with BIS.Results and Discussion: With the improvements introduced, the exhaled propofol can now be monitored with a reproducible method, in which variations in the propofol infusion generate changes in exhaled propofol concentration. In the preliminary results, these changes correlate with all plasma concentration, effect concentration and BIS. Preliminary results reveal that the average concentrations of propofol in air are of 48ppb for Plasmatic TCI concentrations of 2.5 mcg/ml, 55ppb for 3mcg/ml and 68ppb for 4mcg/ml we will have to wait for the completion of the study to offer more consistent and definitive results.Conclusion(s): Improvements introduced in the sample system together with the automation of data collection, allow us to perform studies in large series of patients with reproducibility and accuracy. If the results are confirmed, it could be possible to use this technique as a non invasive propofol monitoring. It would also lead to think that, in the future, a propofol pharmacokinetic model of the lung could be defined.
[Hansen2013] "Recovery of Odorants from an Olfactometer Measured by Proton-Transfer-Reaction Mass Spectrometry",
, vol. 13, no. 6: Multidisciplinary Digital Publishing Institute, pp. 7860–7871, 2013.
The aim of the present study was to examine the recovery of odorants during the dilution in an olfactometer designed according to the European standard for dynamic olfactometry. Nine odorants in the ppmv-range were examined including hydrogen sulfide, methanethiol, dimethyl sulfide, acetic acid, propanoic acid, butanoic acid, trimethylamine, 3-methylphenol and n-butanol. Each odorant was diluted in six dilution steps in descending order from 4,096 to 128 times dilutions. The final recovery of dimethyl sulfide and n-butanol after a 60-second pulse was only slightly affected by the dilution, whereas the recoveries of the other odorants were significantly affected by the dilution. The final recoveries of carboxylic acids, trimethylamine and 3-methylphenol were affected by the pulse duration and the signals did not reach stable levels within the 60-second pulse, while sulfur compounds and n-butanol reach a stable signal within a few seconds. In conclusion, the dilution of odorants in an olfactometer has a high impact on the recovery of odorants and when olfactometry is used to estimate the odor concentration, the recoveries have to be taken into consideration for correct measurements.