Development of a Multibed Sorption Trap, Comprehensive Two-Dimensional Gas Chromatography, and Time-of-Flight Mass Spectrometry System for the Analysis of Volatile Organic Compounds in Human Breath

Abstract

A method for the determination of volatile organic compounds (VOCs) at sub-trace levels in breath samples based on a multibed sorption trap for the collection and concentration of VOCs, a comprehensive multidimensional gas chromatograph (GCxGC) for the separation of complex mixtures, and a time-of-flight mass spectrometer detector is designed and developed. The good performance of the trap tube device developed for the concentration together with the high sensitivity and separation power of the GCxGC results in a powerful system. In the analysis of samples, more than 100 different compounds are detected of which between 65 and 85 are clearly identified. A total of approximately 250 different compounds are observed in all the samples evaluated of which 142 are identified. A preliminary study to evaluate breath biomarkers for active smoking is performed. The levels of previously described biomarkers are found to be strongly time-dependent with amounts found approximately 1 h after smoking returning to the levels found in nonsmoking volunteers. However, 2,5-dimethylfuran, 2-methylfuran, and furan are found to be effective biomarkers given that they were only found in samples taken from smokers and could still be detected more than 2 h after smoking.

Capillary thermal desorption unit for near real-time analysis of VOCs at sub-trace levels. Application to the analysis of environmental air contamination and breath samples

“…A c c e p t e d M a n u s c r i p t 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 12 Similar trap configurations to the one used in this study have previously been described using four-bed [17,20] and three-bed configurations [14]. The use of a three-bed trap is adequate for the analysis of breath samples and a previous study has managed to detect more than 250 VOCs using this configuration [14].…”

“…As there is no single sorbent material that meets the full ideal criteria for concentrating all VOCs from an air matrix, a multi-bed trap must be used for this purpose [17,18]. In this study, we used a three-bed trap for general breath monitoring as it has been found to be effective in analyzing common VOCs present in breath samples [14]. Quantities of 2.5±0.2 mg of Carboxen 1000 and Carbopack X A vacuum pump (Air Cadet Vacuum Station, Barnant Co., Barrington, IL, USA) was used to pull sample gas from left to right through the trap tube shown in Figure 1 at a sample flow rate of 31 cm 3 ·min -1 .…”

“…In the case of breath samples, this problem is aggravated due to the presence of substantial amounts of water vapor. A previous study [14] shows that this configuration helps to maintain the pneumatic conditions in the separation column during the sampling process and prevent thermal decomposition on the surface of the carbon-based sorbents of the most reactive compounds in the samples. …”

“…The possibility of using breath tests to evaluate exposure to ETS is very promising given that it is a procedure that is safe and easy to perform. Preliminary studies have suggested that some VOCs detected in breath samples may be biomarkers (e.g., 1,3-butadiene, benzene, 2,5-dimethylfuran) [8][9][10][11][12][13][14][15][16].…”

“…In order to obtain very rapid heating with a minimal overshoot, a current pulse was applied to the trap for 0.9 s increasing the temperature from 25ºC to the desired desorption temperature (~300ºC). The use of a second low current pulse to maintain the trap temperature, as described in previous studies [14,17], was not necessary as all the adsorbed compounds are quantitatively desorbed with the first pulse. A c c e p t e d M a n u s c r i p t 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 8 (Thermo Scientific, Waltham, MA, USA) with a mass spectrometer detector (DSQ II, Thermo Scientific) was used.…”