[Aprea2012]
Aprea, E., F. Morisco, F. Biasioli, P. Vitaglione, L. Cappellin, C. Soukoulis, V. Lembo, F. Gasperi, G. D'Argenio, V. Fogliano, et al.,
"Analysis of breath by proton transfer reaction time of flight mass spectrometry in rats with steatohepatitis induced by high-fat diet.",
J Mass Spectrom, vol. 47, no. 9: IASMA Research and Innovation Centre, Fondazione Edmund Mach, Food Quality and Nutrition Department, Via E. Mach, 1, 38010, S. Michele a/A, Italy. eugenio.aprea@iasma.it, pp. 1098–1103, Sep, 2012.
Link:
http://dx.doi.org/10.1002/jms.3009
Breath testing has been largely used as a diagnostic tool, but the difficulties in data interpretation and sample collection have limited its application. We developed a fast (< 20?s), on-line, non-invasive method for the collection and analysis of exhaled breath in awake rats based on proton transfer reaction time of flight mass spectrometry (PTR-ToF-MS) and applied it to investigate possible relationships between pathologies induced by dietary regime and breath composition. As a case study, we investigated rats with dietary induced non-alcoholic steatohepatitis (NASH) and modifications induced by coffee addition to the diet. We considered two different diets (standard and high fat) complemented with two different drinking possibilities (water or decaffeinated coffee) for a total of four groups with four rats each. Several spectrometric peaks were reliable markers for both dietary fat content and coffee supplementation. The high resolution and accuracy of PTR-ToF-MS allowed the identification of related compounds such as methanol, dimethyl sulphide, dimethyl sulphone and ammonia. In conclusion, the rapid and minimally invasive breath analysis of awake rats permitted the identification of markers related to diet and specific pathologic conditions and provided a useful tool for broader metabolic investigations.
[Schuhfried2012]
Schuhfried, E., E. Aprea, L. Cappellin, C. Soukoulis, R. Viola, T. D. Maerk, F. Gasperi, and F. Biasioli,
"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.
Link:
http://www.sciencedirect.com/science/article/pii/S1387380612000292
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. [7] 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.
[Tasin2012]
Tasin, M., L. Cappellin, and F. Biasioli,
"Fast direct injection mass-spectrometric characterization of stimuli for insect electrophysiology by proton transfer reaction-time of flight mass-spectrometry (PTR-ToF-MS).",
Sensors (Basel), vol. 12, no. 4: IASMA Research and Innovation Centre, Fondazione Edmund Mach, San Michele all'Adige, Italy. marco.tasin@slu.se, pp. 4091–4104, 2012.
Link:
http://dx.doi.org/10.3390/s120404091
Electrophysiological techniques are used in insect neuroscience to measure the response of olfactory neurons to volatile odour stimuli. Widely used systems to deliver an olfactory stimulus to a test insect include airstream guided flow through glass cartridges loaded with a given volatile compound on a sorbent support. Precise measurement of the quantity of compound reaching the sensory organ of the test organism is an urgent task in insect electrophysiology. In this study we evaluated the performances of the recent realised proton transfer reaction-time of flight mass-spectrometry (PTR-ToF-MS) as a fast and selective gas sensor. In particular, we characterised the gas emission from cartridges loaded with a set of volatile compounds belonging to different chemical classes and commonly used in electrophysiological experiments. PTR-ToF-MS allowed a fast monitoring of all investigated compounds with sufficient sensitivity and time resolution. The detection and the quantification of air contaminants and solvent or synthetic standards impurities allowed a precise quantification of the stimulus exiting the cartridge. The outcome of this study was twofold: on one hand we showed that PTR-ToF-MS allows monitoring fast processes with high sensitivity by real time detection of a broad number of compounds; on the other hand we provided a tool to solve an important issue in insect electrophysiology.
[JLTing2012]
Ting, V. J. L., C. Soukoulis, P. Silcock, L. Cappellin, A. Romano, E. Aprea, P. J. Bremer, T. D. Märk, F. Gasperi, and F. Biasioli,
"In Vitro and In Vivo Flavor Release from Intact and Fresh-Cut Apple in Relation with Genetic, Textural, and Physicochemical Parameters",
Journal of food science, vol. 77, no. 11: Wiley Online Library, pp. C1226–C1233, 2012.
Link:
http://onlinelibrary.wiley.com/doi/10.1111/j.1750-3841.2012.02947.x/full
Flavor release from 6 commercial apple cultivars (Fuji, Granny Smith, Golden Delicious, Jonagold, Morgen Dallago, and Red Delicious) under static conditions (intact or fresh-cut samples) and during consumption of fresh-cut samples (nosespace) was determined by proton transfer reaction mass spectrometry. Textural (firmness, fracturability, flesh elasticity, and rupture) and physicochemical (pH, acidity, and water content) properties of the apples were also measured. Static headspace analysis of intact fruits revealed Fuji and Granny Smith apples had the lowest concentration for all measured flavor compounds (esters, aldehydes, alcohols, and terpenes), whereas Red Delicious apples had the highest. Fresh-cut samples generally showed a significant increase in total volatile compounds with acetaldehyde being most abundant. However, compared to intact fruits, cut Golden and Red Delicious apples had a lower intensity for ester related peaks. Five parameters were extracted from the nosespace data of peaks related to esters (m/z 43, 61), acetaldehyde (m/z 45), and ethanol (m/z 47): 2 associated with mastication (duration of mastication–tcon; time required for first swallowing event–tswal), and 3 related with in-nose volatile compound concentration (area under the curve–AUC; maximum intensity–Imax; time for achieving Imax–tmax). Three different behaviors were identified in the nosespace data: a) firm samples with low AUC and tswal values (Granny Smith, Fuji), b) mealy samples with high AUC, Imax, tswal values, and low tcon (Morgen Dallago, Golden Delicious), and c) firm samples with high AUC and Imax values (Red Delicious). Strengths and limitations of the methodology are discussed.
[Ting2012]
Ting, V. J. L., C. Soukoulis, P. Silcock, L. Cappellin, A. Romano, E. Aprea, P. J. Bremer, T. D. Maerk, F. Gasperi, and F. Biasioli,
"In vitro and in vivo flavor release from intact and fresh-cut apple in relation with genetic, textural, and physicochemical parameters.",
J Food Sci, vol. 77, no. 11: Research and Innovation Centre, Foundation Edmund Mach, via Mach 1, San Michele all' Adige, (TN), Italy., pp. C1226–C1233, Nov, 2012.
Link:
http://dx.doi.org/10.1111/j.1750-3841.2012.02947.x
Flavor release from 6 commercial apple cultivars (Fuji, Granny Smith, Golden Delicious, Jonagold, Morgen Dallago, and Red Delicious) under static conditions (intact or fresh-cut samples) and during consumption of fresh-cut samples (nosespace) was determined by proton transfer reaction mass spectrometry. Textural (firmness, fracturability, flesh elasticity, and rupture) and physicochemical (pH, acidity, and water content) properties of the apples were also measured. Static headspace analysis of intact fruits revealed Fuji and Granny Smith apples had the lowest concentration for all measured flavor compounds (esters, aldehydes, alcohols, and terpenes), whereas Red Delicious apples had the highest. Fresh-cut samples generally showed a significant increase in total volatile compounds with acetaldehyde being most abundant. However, compared to intact fruits, cut Golden and Red Delicious apples had a lower intensity for ester related peaks. Five parameters were extracted from the nosespace data of peaks related to esters (m/z 43, 61), acetaldehyde (m/z 45), and ethanol (m/z 47): 2 associated with mastication (duration of mastication-t(con); time required for first swallowing event-t(swal)), and 3 related with in-nose volatile compound concentration (area under the curve-AUC; maximum intensity-I(max); time for achieving I(max)-t(max)). Three different behaviors were identified in the nosespace data: a) firm samples with low AUC and t(swal) values (Granny Smith, Fuji), b) mealy samples with high AUC, I(max), t(swal) values, and low t(con) (Morgen Dallago, Golden Delicious), and c) firm samples with high AUC and I(max) values (Red Delicious). Strengths and limitations of the methodology are discussed. PRACTICAL APPLICATION: Volatile compounds play a fundamental role in the perceived quality of food. Using apple cultivars, this research showed that in vivo proton transfer reaction mass spectrometry (PTR-MS) could be used to determine the relationship between the release of volatile flavor compounds and the physicochemical parameters of a real food matrix. This finding suggests that in vivo PTR-MS coupled with traditional physicochemical measurements could be used to yield information on flavor release from a wide range of food matrices and help in the development of strategies to enhance food flavor and quality.