Flow injection analysis (FIA), which is an advanced method of continuous flow analysis (CFA), was conceived in Denmark by Ruzicka and Hansen in 1974, and the first paper describing this novel and revolutionizing analytical concept for conducting chemical assays was published in early 1975. The lab-on-a-valve (LOV) concept encompasses many of the features of SIA. In fact, LOV can be regarded as a sequel of sequential injection analysis (SIA) by smart modification of the stator of the multiposition valve. A valuable asset of the LOV structure is the micro/meso fluidic handling capabilities of not only metered volumes of solutions but solid suspensions as well for exploitation of heterogeneous chemical reactions. Miniaturized membrane-based separation in custom-made LOV modules was allied to cold vapor generation systems prior to atomic fluorescence spectrometry. In the early 1990s, a variant of FIA was introduced, that is, sequential injection analysis, named SIA or System of Units.