VOCs in Human Breath
Conventional ‘off-line’ gas analysis equipment struggles with using VOCs as a real-time marker for lactate threshold, and oxidative stress due to the fast response times and wide dynamic range required. There are major benefits to monitoring breath VOCs, as analysis of physiological events could be undertaken in real-time in a safe, non-invasive manner.
Figure 1. The Hiden HPR-20 Transient MS
The HPR-20 Transient MS is perfect for this application as it fast response times, wide dynamic range and it’s highly sensitive PIC detector. It can therefore measure compounds breath-by-breath, which is vastly superior to that offered by traditional ‘off-line’ techniques. Additional dynamic factors such as changes in breathing rate and end-tidal could be deduced.
Figure 2. Example data showing the real-time analysis of muliple compounds exhaled in human breath during an exercise test.
For the experiment, the subject was fitted with a proprietary breathing mask, which was in turn connected to the HPR-20 QIC TMS via a customized adaptor, optimized for high speed analysis. The test used a group of subjects with various ages and fitness levels, who were set a maximal exercise test on a stationary bicycle and their breath was then monitored in real-time. Known as a ‘ramp test’, the resistance of the bicycle was ramped up over time in order to push the subject to their aerobic capacity.
Data obtained from the experiments allowed the real-time tracking of multiple compounds were produced in varying amounts during aerobic and anaerobic respiration. With a time resolution of only 20 ms, the subjects every breath could be monitored for concentration of compounds. Inflections were seen in the data points that could relate to physiological changes in the subject, such as lactate threshold.
This rapid monitoring and analyses of VOC compounds during physiological events is a new technique and is not easily done via other methods. As seen in Figure 2 the fast response of the HPR-20 QIC Transient MS, allows each breath to be tracked. In contrast to conventional off-line techniques, parameters such as breathing rate as well as end tidal can be readily deduced.
- The Hiden HPR-20 QIC TMS is shown to be the ideal product for high speed, high sensitivity analysis of compounds in human breath.
- Real time analysis of exhaled species is a novel research tool.
- The excellent response time and dynamic range offered by the HPR- 20 allow the concentration changes of multiple compounds to be measured in real time.
This information has been sourced, reviewed and adapted from materials provided by Hiden Analytical.
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