High-resolution mass spectrometry

Abstract High-resolution mass spectrometry (HRMS) can determine the masses of compounds with much greater precision than low-resolution mass spectrometers, with mass differences as low as 0.0001 Da, making it possible to distinguish between compounds based on exact mass rather than integer mass. Traditionally, many studies have relied on low-resolution mass spectrometry due to its widespread availability and lower cost; however, HRMS has many advantages for breath research applications. In this chapter, the fundamental concepts of HRMS are presented and discussed, as are popular types of mass analyzer, including time-of-flight (TOF), Orbitrap, and Fourier-transform ion cyclotron resonance (FT-ICR). The usefulness of HRMS for nontargeted analyses of complex breath samples to detect unknown compounds that may be important for assessing health state or environmental exposure of individuals is discussed, and the current techniques that are being used to analyze exhaled breath, exhaled breath condensate (EBC), and exhaled breath aerosol (EBA) matrices are highlighted.