From molecules in space to molecules in breath.

The evolution of the selected ion flow tube, SIFT, used to study ion-molecule reactions of interstellar significance, to the selected ion flow tube mass spectrometry, SIFT-MS, analytical technique is described briefly. Focus is placed on the application of SIFT-MS to breath analysis and its potential for the detection of volatile biomarkers of disease including respiratory pathogens. Typical concentrations of particular volatile breath biomarkers are given and their associations with specific diseases are indicated. A special case is the identification and quantification of gaseous hydrogen cyanide that is elevated in the exhaled breath of patients with cystic fibrosis and is now taken as a biomarker of Pseudomonas aeruginosa infection of the airways.