Analytical approaches for disease detection

Analytical technologies represent the core of volatile biomarker detection in human health applications. A wide range of techniques exist, each exhibiting a varying degree of complexity, from comprehensive laboratory-based instrumentation to portable handheld sensor systems. Each tool has unique features that make it suitable for its specified application in the detection of volatile organic compounds (VOCs) as biomarkers in human health. This chapter reviews the most common and applicable analytical approaches for VOC detection in diverse bodily fluids, primarily in exhaled breath, as well as in urine, sweat and feces. Technologies covered in this chapter include gas chromatography–mass spectrometry (GC–MS), including multidimensional GC–MS (GC × GC–MS and GC–GC–MS), real-time mass spectrometry, including proton transfer reaction-mass spectrometry (PTR-MS), selected ion flow tube-mass spectrometry (SIFT-MS) and secondary electrospray ionization-mass spectrometry (SESI-MS), as well as ion mobility spectrometry (IMS) and optical spectroscopy. The chapter covers the basic operating principles of these key techniques in the analysis and detection of VOCs and offers an overview of representative studies that demonstrate their strengths and suitability relating to volatile biomarker detection in human health applications.