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Fields & Applications Spectroscopy

Breath Analysis with a (Very) Fine Toothed Comb

GC-MS is the most widely used analytical technique in breath analysis. But a relatively slow technique that can usually only detect one chemical at a time is impractical for real-world testing. That’s why a group of researchers decided to tackle the problem by using mid-infrared cavity-enhanced direct-frequency comb spectroscopy (CE-DFCS) to simultaneously detect and monitor four health biomarkers – methanol, methane, water and a form of heavy water (HDO) – in the breath of a volunteer (1).

The novel system “fingerprints” chemicals by measuring the amount of light absorbed as a laser frequency comb passes back and forth through breath samples loaded into a mirrored glass tube. Recent upgrades include a shift in the light spectrum analyzed from the near-infrared to the mid-infrared band and advances in optical coatings, both of which have allowed detection sensitivity up to the parts-per-trillion level – a thousandfold improvement.

The researchers are confident that, by extending the comb lasers further into the infrared, they’ll be able to identify many hundreds of trace breath chemicals at once (2).

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  1. Q Liang et al., PNAS, 118, 40 (2021). DOI: 10.1073/pnas.2105063118.
  2. NIST (2021). Available at:
About the Author
James Strachan

Over the course of my Biomedical Sciences degree it dawned on me that my goal of becoming a scientist didn’t quite mesh with my lack of affinity for lab work. Thinking on my decision to pursue biology rather than English at age 15 – despite an aptitude for the latter – I realized that science writing was a way to combine what I loved with what I was good at.

From there I set out to gather as much freelancing experience as I could, spending 2 years developing scientific content for International Innovation, before completing an MSc in Science Communication. After gaining invaluable experience in supporting the communications efforts of CERN and IN-PART, I joined Texere – where I am focused on producing consistently engaging, cutting-edge and innovative content for our specialist audiences around the world.


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