New Trends in Flow Injection Analysis: Exploitation of Sequential and Lab-on-Valve Schemes

Over the past 25 years, Flow Injection Analysis (FIA) has established itself as an indispensable analytical concept that not only has permitted the implementation of numerous intriguing analysis procedures. But, more importantly, it has made it possible to facilitate the execution of procedures which are difficult or, in fact, otherwise impossible to do, thereby opening new and novel avenues for analytical methods relying on concepts such as kinetic discriminations schemes, exploitation of metastable constituents of attractive analytical characteristics, or utilisation of detection by bio- and chemiluminescence. In recent years, FIA has been supplemented by Sequential Injection Analysis (SIA), which, although it inherently entails some limitations as compared to FIA, offers specific advantages, especially concerning sample and reagent(s) consumption. Most recently, the socalled third generation of FIA has appeared, that is, the Lab-on-Valve (LOV) approach, the conceptual basis of which is to incorporate all the necessary unit operational manipulations required, and, when possible, even the detection device into a single small integrated microconduit, or “laboratory”, placed atop a selection valve. The lecture will detail the evolution of the three generations of FIA, emphasis being placed on the SIA and especially the LOV systems. The practical utility of the latter one will be exemplified by a series of applications, including its use as a vehicle for pretreatment of samples for determination by electrothermal atomic absorption spectrometry (ETAAS) and inductively coupled plasma mass spectrometry (ICPMS). Despite their excellent analytical chemical capabilities, these detection devices, nevertheless, often require that the samples are subjected to suitable pretreatment in order to obtain the necessary sensitivity and selectivity. Either in order to separate/preconcentrate the analyte material, or because of the presence of potentially interfering matrix constituents. Such pretreatments are advantageously performed in FIA/SIA/LOV manifolds, where all appropriate unit operations can be effected under enclosed and strictly controlled conditions.