ABSTRACT
Liquid chromatography–mass spectrometry (LC–MS) based on atmosphericpressure ionization (API) was demonstrated as early as 1974 (Ch. 3.2.1). However, it took until the late 1980's before API was starting to be widely applied. Today, it can be considered by far the most important interfacing strategy in LC–MS. More than 99% of the LC–MS performed today is based on API interfacing. In this chapter, instrumentation for API interfacing is discussed. First, vacuum system for MS and LC–MS are briefly discussed. Subsequently, attention is paid to instrumental and practical aspects of electrospray ionization (ESI), atmospheric-pressure chemical ionization (APCI), and other interfacing approaches based on API. The emphasis in the discussion is on commercially available systems and modifications thereof. Ionization phenomena and mechanisms are dealt with in a separate chapter (Ch. 6). Laser-based ionization for LC–MS is briefly reviewed (Ch. 5.9).
