Selected ion flow tube mass spectrometry

Selected ion flow tube mass spectrometry (SIFT-MS) is a chemical ionization technique that offers sensitive, real-time detection of volatile organic compounds (VOCs) down to trace levels. This chapter briefly introduces the technique and summarizes the recent research into SIFT-MS analyses of exhaled breath and the most pertinent results obtained. The search for single-breath VOCs is illustrated by the online quantification by SIFT-MS of ammonia, acetone, hydrogen cyanide, methanol, pentane, and acetic acid. The breathprint approach to the analysis of SIFT-MS spectra is illustrated by several studies of the exhaled breath of patients with several clinical conditions, including heart failure and liver disease. The results of detailed breath SIFT-MS studies in patients with gastroesophageal cancer indicate that VOC profiling may be suitable in identifying those at high risk of this disease. In vitro studies of the VOCs emitted by pulmonary pathogens illustrate the search for exhaled breath biomarkers of airways colonization by such organisms.