Online Breath Sampling

In the medical area, one study using DART has been applied to human breath. Diagnosis through online breath analysis was fonnd to be difficult due to the dispersion of the breath samples in open air. A confined DART ion source (cDART) was developed and this was tested on fonr standard compounds—ethanol, acetone, 2-hexanone, and limonene— with detection limits approaching 1 ppbv after calibration [188]. 

At the time of writing, no standard procedure has been adopted. In the next few sections, we discuss possible breath collection procedures, both for online and offline sampling. 

The use of PTR-MS in medical science is not just restricted to breath analysis and online in vitro measurements of microbial cultures. PTR-MS has considerable potential for application in other medical areas, such as the analysis of the headspace above liquid and solid biological samples (e.g. urine, faeces or sputum samples) or detecting emissions from skin (a potential application being the early detection of skin cancers), but surprisingly there have been only a limited number of such studies at the time of writing. Furthermore, with the development of direct aqueous injection inlet systems (see Section 9.2), PTR-MS is not just limited to headspace analysis but now also has the potential to analyse liquid samples directly. 

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