Exhaled air analysis

Periago JF, Cardona A, Marhuenda D, et al. 1993. Biological monitoring of occupational exposure to -hexane by exhaled air analysis and urinalysis. Int Arch Occup Environ Health 65 275-278. 

Keywords Chemical sensors Point contact Exhaled air analysis Point-contact spectroscopy Organic conductors Noninvasive diagnostics Chronic dyspepsia... 

Several methods are available for the analysis of trichloroethylene in biological media. The method of choice depends on the nature of the sample matrix cost of analysis required precision, accuracy, and detection limit and turnaround time of the method. The main analytical method used to analyze for the presence of trichloroethylene and its metabolites, trichloroethanol and TCA, in biological samples is separation by gas chromatography (GC) combined with detection by mass spectrometry (MS) or electron capture detection (ECD). Trichloroethylene and/or its metabolites have been detected in exhaled air, blood, urine, breast milk, and tissues. Details on sample preparation, analytical method, and sensitivity and accuracy of selected methods are provided in Table 6-1. 

The aim of the study was to create high-sensitive point-contact type gas sensors based on derivatives of 7,7,8,8-tetracyanoquinodimethane (TCNQ) and to test them in analysis of exhaled air for diagnosis and monitoring of human organism state. 

Due to a combination of the modified technique for sensor analysis of composite gas mixture with unique properties of the gas-sensitive point-contact matrix, a complex dynamic of interaction between sensitive matter and volatile compounds of exhaled air has been observed. This interaction is characterized by longer adsorption times. This behavior was not observed in our previous work on breath analysis where fihn samples were used [11]. 

SIFT-MS was used for the analysis of VOCs present in air samples [127]. Substances such as ammonia, isoprene, acetone, ethanol, and acetonitrile were detected at ppb levels. SIFT-MS was also applied to analysis of blood [126], urine [128], food [129], and headspace from lung cancer cells [130]. The spectrum of exhaled air is presented in Fig. 14.10. 

GC coupled with IMS has many advantages and is applied for quality control in the pharmaceutical industry [131, 132] and for detection of trace amount of explosives, warfare agents, and drugs [133-135]. This system is used to monitor ambient air [136] and for direct analysis of exhaled air [137]. 

Campbell L, Jones AH, Wilson HK. 1985. Evaluation of occupational exposure to carbon disulphide by blood, exhaled air, and urine analysis. Am J Ind Med 8 143-153. 

The general aim of this chapter is to contribute to the establishment of a fast and low-cost device for human breath analysis in addition to inveshgahons of blood and urine as a non-invasive standard method in hospitals and point-of-care centers for different medical apphcahons. On the basis of miniaturized ion mobihty spectrometry (IMS), the fuU procedure, including sampling, pre-separahon and idenhficahon of metabolites in human exhaled air, will be developed and implemented with re-... 

By coupling IMS and a MCC for pre-separation, investigations were carried out to directly detect volatile metabolites in human exhaled air. The total analysis was re-... 

Another interesting application of microwave energy was reported by Mueller et al The authors studied the amount of benzene and alkylated benzenes (BTX) in ambient and exhaled air by microwave desorption coupled to GC-MS. Microwave desorption was proved as an effective sample preparation technique for the analysis of BTX in air samples. A similar desorption technique was applied for the GC analysis of nicotine in indoor air as well. "... 

Mueller, W., Schubert, J., Benzing, A., and Geiger, K., Method for analysis of exhaled air by microwave energy desorption coupled with gas chromatography-flame ionization detection-mass spectrometry, J. Chromatogr. B, 716, 27-38, 1998. 

The analysis for metal ultratraces requires extremely clean laboratories [2]. This, in turn, requires the use of a carefully filtered air supply. All reagents used must be certifledly ultrapure and their purity be preserved. Deionized water should be carefully controlled to ascertain the absence of contaminating traces —this requires all technicians to exercise care to avoid contamination by their hair, skin, cosmetics, excretions or even the exhaled air. A strict control of the analytical blank [3] Is obviously another must in this type of analysis to avoid spurious results In the determination of some trace or ultratrace analytes. 

Styrene may be analyzed by GC, nsing a flame ionization detector. Air analysis may be performed by charcoal adsorption, followed by desorption of the analyte with carbon disnl-fide and injection of the elnant into GC-FID (NIOSH Method 1501 see Section 26.2). Styrene intake in the body may be estimated by analyzing mandelic acid in the nrine by liquid chromatography, polarography, or GC. However, the presence of other aromatics may interfere, as these componnds also generate the same urinary metabolite. Styrene in exhaled air may be analyzed by absorption over ethanol or charcoal followed by GC, UV, or IR analysis. 

Experimentally, the RER is obtained by analysis of the inhaled and exhaled air of the person exercising. 

A variety of sampling techniques has been tried for measuring organic vapors in exhaled air. Table 15.2.1.1 shows a classification of these techniques. The main distinction is between direct reading instruments and transportable samples that require analysis in the laboratory. The former group covers the widest range, from simple detector tubes to High Resolution Mass Spectrometry. 

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