[Miekisch2012] "Data interpretation in breath biomarker research: pitfalls and directions",
Journal of Breath Research
, vol. 6, no. 3, pp. 036007, 2012.
[Bamberger2012] "Deposition of terpenes to vegetation-a paradigm shift towards bidirectional VOC exchange?",
EGU General Assembly Conference Abstracts
, vol. 14, pp. 7949, 2012.
Biogenic volatile organic compounds (BVOCs) are important precursors for secondary organic aerosol (SOA) formation (Hallquist et al., 2009). In addition reactive BVOCs play a crucial role in local tropospheric ozone production (Atkinson, 2000). According to the present scientific understanding vegetation is recognized as a major VOC emission source rather than a deposition sink. Our recent observations however demonstrate that an uptake of terpene compounds to mountain grassland can be significant - at least under certain atmospheric conditions. After a severe hailstorm volume mixing ratios (VMR) of locally emitted terpene compounds originating from conifers located at the mountain slopes were strongly enhanced, even during daytime hours. Weeks after the hailstorm our PTR-MS and PTR-time-of-flight (PTR-TOF) instruments still measured deposition fluxes of monoterpenes (m/z 137.133), sesquiterpenes (m/z 205.195), and oxygenated terpenes (m/z 153.128) to the grassland. The total amount of terpenoids (on a carbon basis) deposited to the grassland during the weeks after the hailstorm is comparable to the total methanol emission of the entire growing season (Bamberger et al., 2011). These findings pose the question whether the terminology should be adjusted from VOC emission to VOC exchange.
[Sulzer2012a] "Designer Drugs and Trace Explosives Detection with the Help of Very Recent Advancements in Proton-Transfer-Reaction Mass Spectrometry (PTR-MS)",
: Springer, pp. 366–375, 2012.
At the "Future Security 2011" we presented an overview of our studies on the "Detection and Identification of Illicit and Hazardous Substances with Proton-Transfer-Reaction Mass Spectrometry (PTR-MS)" including first results on explosives, chemical warfare agents and illicit and prescribed drugs detection. Since then we have considerably extended these preliminary studies to the detection of defined traces of some of the most common explosives, namely TNT, PETN, TATP, and DATP deposited into aluminum foam bodies, and to the detection of a number of novel and widely unknown designer drugs: ethylphenidate, 4-fluoroamphetamine and dimethocaine. Moreover, we have dramatically improved our time-of-flight based PTR-MS instruments by substantially increasing their sensitivity and hence lowering the detection limit, making them even more suitable and applicable to threat agents with extremely low vapour pressures. Data from measurements on certified gas standards are presented in order to underline these statements. The data demonstrate that, in comparison to the first generation instruments, a gain of one order of magnitude in terms of sensitivity and detection limit has been obtained.
[Schuhfried2012] "Desorption kinetics with PTR-MS: Isothermal differential desorption kinetics from a heterogeneous inlet surface at ambient pressure and a new concept for compound identification",
International journal of mass spectrometry
, vol. -: Elsevier, pp. -, 2012.
Proton transfer reaction-mass spectrometry (PTR-MS) is a soft ionization mass spectrometric technique for monitoring volatile organic compounds (VOCs) with a very low limit of detection (LOD) (parts per trillion by volume) and excellent time resolution (split seconds). This makes PTR-MS a particularly interesting instrument for investigating surface desorption kinetics of volatile organic compounds (VOCs) under realistic conditions, i.e., at ambient pressure from a heterogeneous surface. Here, we report on the investigation of heterogeneous inlet surface kinetics with PTR-MS and based thereon, develop concepts to assist compound identification in PTR-MS. First, we studied differential isothermal desorption kinetics using heterogeneous inlet surface data measured by Mikoviny et al.  with their newly developed high-temp-PTR-MS. The best fit to their data is obtained with bimodal pseudo-first order kinetics. In addition, we explored the normalization of the data and calculated data points of the desorption isotherms. We found evidence that the interesting part of the isotherm can be linearized in a double log plot. Then we investigated the idea to use memory effects of the inlet system to assist compound identification. At the moment, the main problem is the dependence of the kinetics on the initial equilibrium gas phase adsorption concentration, and thus, the surface coverage. As a solution, we suggest an empirical, quasi-concentration independent, yet compound specific parameter: the normalized desorption time tnd describing the decline of the signal to 1/e2 of the initial concentration, normalized to an initial concentration of 10,000 counts per second (cps). Furthermore, we investigated property–property and structure–property relationships of this new parameter. Further possible improvements are discussed as well.
[Kassebacher2012] "Detecting and Quantifying Toxic Industrial Compounds (TICs) with Proton-Transfer-Reaction Mass Spectrometry (PTR-MS)",
: Springer, pp. 438–447, 2012.
In the course of the FP7-SEC project "SPIRIT" (Safety and Protection of built Infrastructure to Resist Integral Threats) we focused our research with Proton-Transfer-Reaction Mass Spectrometry (PTR-MS) on C-agents, specifically Toxic Industrial Compounds (TICs). Most TICs are readily available and represent a considerable threat when used in terroristic attacks. We show the principal procedure of PTR-MS detection measurements on two chemicals, namely phosgene and chloroacetone. With studies of the former we want to point out principle differences between measurements on a quadrupole mass filter based and a Time-of-Flight-based PTR-MS instrument and point out the respective benefits and drawbacks. For the latter we present the results of a diluted headspace measurement and illustrate the connection with security standards in buildings.
[Zehm2012] "Detection of Candida albicans by mass spectrometric fingerprinting.",
, vol. 64, no. 3: Department of Vascular Surgery, Innsbruck University Hospital, Anichstrasse 35, Innsbruck, Austria. email@example.com, pp. 271–275, Mar, 2012.
<p>Candida albicans is one of the most frequent causes of fungal infections in humans. Significant correlation between candiduria and invasive candidiasis has previously been described. The existing diagnostic methods are often time-consuming, cost-intensive and lack in sensitivity and specificity. In this study, the profile of low-molecular weight volatile compounds in the headspace of C. albicans-urine suspensions of four different fungal cell concentrations compared to nutrient media and urine without C. albicans was determined using proton-transfer reaction mass spectrometry (PTR-MS). At fungal counts of 1.5 x 10(5) colony forming units (CFU)/ml signals at 45, 47 and 73 atomic mass units (amu) highly significantly increased. At fungal counts of <1.5 x 10(5) CFU/ml signals at 47 and 73 amu also increased, but only at 45 amu a statistically significant increase was seen. Time course alterations of signal intensities dependent on different cell concentrations and after addition of Sabouraud nutrient solution were analysed. Recommendations for measurement conditions are given. Our study is the first to describe headspace profiling of C. albicans-urine suspensions of different fungal cell concentrations. PTR-MS represents a promising approach to rapid, highly sensitive and non-invasive clinical diagnostics allowing qualitative and quantitative analysis.</p>
[Agarwal2012] "Detection of isocyanates and polychlorinated biphenyls using proton transfer reaction mass spectrometry.",
Rapid Commun Mass Spectrom
, vol. 26, no. 8: Institut fuer Ionenphysik und Angewandte Physik, Leopold Franzens Universitaet Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria., pp. 983–989, Apr, 2012.
Isocyanates are highly reactive species widely used in industry. They can cause irritation of the eyes, trigger asthma, etc. Polychlorinated biphenyls (PCBs) were widely used in electrical equipments like capacitors and transformers in the last century and are still present in the environment today. PCBs are known to cause cancer and to affect the immune, reproductive, nervous and endocrine systems. Therefore, there is a need for a simple, rapid and reliable analytical method for the detection of traces of isocyanates and of PCBs.The data presented in this paper were obtained using a proton transfer reaction (PTR) time-of-flight mass spectrometer and a high sensitivity PTR quadrupole mass spectrometer. We also utilized a recently developed direct aqueous injection (DAI) inlet system for proton transfer reaction mass spectrometry (PTR-MS) instruments that allows the analysis of trace compounds in liquids.We detected four isocyanates in the headspace above small sample quantities and investigated their fragmentation pathways to obtain a fundamental understanding of the processes involved in proton transfer reactions and also to determine the best operating conditions of the PTR-MS instruments. In addition, nine PCBs were unambiguously identified via their exact mass and isotopic distribution and detected in different concentration levels via direct injection of the liquid.Utilizing recent developments and improvements in PTR-MS, we can rapidly detect two important environmental pollutant compound classes (isocyanates and PCBs) at high accuracy and without any sample preparation. In this paper, we provide proof of the detection of traces of isocyanates and PCBs in air and also of PCBs in liquids. These results could be used for the development of a real-time monitoring device for industrial waste, polluted air or water quality surveillance.
[Knighton2012] "Direct measurement of volatile organic compound emissions from industrial flares using real-time online techniques: Proton Transfer Reaction Mass Spectrometry and Tunable Infrared Laser Differential Absorption Spectroscopy",
Industrial & Engineering Chemistry Research
, vol. 51, no. 39: ACS Publications, pp. 12674–12684, 2012.
During the 2010 Comprehensive Flare Study a suite of analytical instrumentation was employed to monitor and quantify in real-time the volatile organic compound (VOC) emissions emanating from an industrial chemical process flare burning either propene/natural gas or propane/natural gas. To our knowledge this represents the first time the VOC composition has been directly measured as a function of flare efficiency on an operational full-scale flare. This compositional information was obtained using a suite of proton-transfer-reaction mass spectrometers (PTR-MS) and quantum cascade laser tunable infrared differential absorption spectrometers (QCL-TILDAS) to measure the unburned fuel and associated combustion byproducts. Methane, ethyne, ethene, and formaldehyde were measured using the QC-TILDAS. Propene, acetaldehyde, methanol, benzene, acrolein, and the sum of the C3H6O isomers were measured with the PTR-MS. A second PTR-MS equipped with a gas chromatograph (GC) was operated in parallel and was used to verify the identity of the neutral components that were responsible for producing the ions monitored with the first PTR-MS. Additional components including 1,3-butadiene and C3H4 (propyne or allene) were identified using the GC/PTR-MS. The propene concentrations derived from the PTR-MS were found to agree with measurements made using a conventional GC with a flame ionization detector (FID). The VOC product (excludes fuel components) speciation profile is more dependent on fuel composition, propene versus propane, than on flare type, air-assisted versus steam-assisted, and is essentially constant with respect to combustion efficiency for combustion efficiencies >0.8. Propane flares produce more alkenes with ethene and propene accounting for approximately 80% (per carbon basis) of the VOC combustion product. The propene partial combustion product profile was observed to contain relatively more oxygenated material where formaldehyde and acetaldehyde are major contributors and account for 20 - 25% of VOC product carbon. Steam-assisted flares produce less ethyne and benzene than air-assisted flares. This observation is consistent with the understanding that steam assisted flares are more efficient at reducing soot, which is formed via the same reaction mechanisms that form benzene and ethyne.