Journal of breath research
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Breath gas analysis is a promising technology for medical applications. By identifying disease-specific biomarkers in the breath of patients, a non-invasive and easy method for early diagnosis or therapy monitoring can be developed. In order to achieve this goal, one essential prerequisite is the reproducibility of the method applied, i.e. the quantification of exhaled volatile organic compounds (VOCs). ⋯ Therefore, a study has been undertaken in order to identify some effects of different breath sampling-specific parameters on the exhaled VOC profile using the mixed expired breath sampling technique. It was found that parameters such as filling the sampling bag with high or low flow rate of exhalation, with multiple or single exhalations, in different volumes of exhalation, with breath holding and under different surrounding air conditions significantly affect the concentrations of the exhaled VOCs. Therefore, the specific results of this work should be taken into account before planning new breath gas studies or developing new breath gas collection systems in order to minimize the number of artefacts affecting the concentration of exhaled VOCs.
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Exhaled breath condensate (EBC) analysis is a non-invasive method to repeatedly evaluate airway inflammation. Dissolved carbon dioxide contributes to lowering EBC pH which is reversed by degassing with argon. Hypothetically, argon may also improve biomarker stability by removing reactive gases, since many markers are pH sensitive or easily oxidized. ⋯ The optimal degassing methods were to bubble the aliquots with argon at 400 ml min(-1) for 60 s or surface degassing for 300 s. Both methods resulted in significantly less EBC volume loss than the commonly adopted method of bubbling for 10 min. There was a significant difference in the H₂O₂ concentration between the degassed and the non-degassed samples.