Real Time Monitoring of Breath VOCs using HPR-20 TMS Transient MS

VOCs in human breath

Traditional ‘offline’ gas analysis instruments such as GCMS find it difficult to use VOCs as a real-time marker to analyze human breath for physiological events oxidative stress and lactate threshold. A wide dynamic range coupled with very fast response is required for the analysis. Monitoring breath VOCs could provide an efficient non-invasive tool to perform real time analysis of physiological events.

For this application, the HPR-20 TMS Transient MS is ideally suited due to the high sensitivity, wide dynamic range, and fast response provided by the PIC detector. As a result, the compounds can be measured “breath-by-breath,” a notable improvement over conventional ‘off-line’ techniques. It is also possible to deduce other dynamic factors such as changes in end tidal and breathing rate.

Figure 1. HPR-20 TMS Transient MS

Experimental setup

The HPR-20 TMS was coupled to a proprietary breathing mask using a customized adaptor, optimized for high speed analysis. A maximal exercise test was performed on a stationary bicycle by subjects of different ages and fitness levels, with real-time monitoring of breath. The test included a common physiological test known as a ‘ramp test’ involving the subject to exercise to their aerobic capacity.


Data collected from the analyses allowed real-time monitoring of multiple compounds generated in varying quantities during anaerobic and aerobic respiration. The concentration of compounds can be monitored in each breath owing to the time resolution of 20 ms per data point.

The data showed inflections at some points which could be associated with the physiological changes taking place in the subject, such as lactate threshold. During physiological events, monitoring changes in VOC compounds is a novel capability which is not easily possible with other techniques.

Figure 2 illustrates the fast response of the HPR-20 TMS Transient MS, enabling the observation of each breath. Unlike conventional off-line techniques, parameters such as breathing rate and end tidal can be readily deduced.

Figure 2. Example data showing the real-time analysis of multiple compounds exhaled in human breath during an exercise test


  • The Hiden HPR-20 TMS is demonstrated to be the suitable product for high speed, high sensitivity analysis of compounds present in human breath
  • Real time analysis of exhaled species provides a novel research tool
  • With excellent dynamic range and response time, the HPR-20 allows real-time measurement of concentration changes of multiple compounds

About Hiden Analytical

Hiden Analytical was founded in 1981 and is presently situated in a 2,130m2 manufacturing plant in Warrington, England with a staff of over 50. As a privately owned company our reputation is built on creating close and positive relationships with their clients.

Hiden Analytical is committed to providing systems which meet specifications of both new and existing clients, but further, enable the advancement of their work, whether it be pure research or the improvements or monitoring of products and process performance.

They have a common vision, not only to supply the systems and instruments with first class performance specifications, long term reliability and professional service support, but also, and in many cases more importantly, to maintain close contact to ensure that our systems provide all that our customers expect, and more, from their investment in our organisation.

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Last updated: Dec 6, 2017 at 9:19 AM