Flow injection analysis system configuration

In single-line (also called straight or single channel) flow systems, the required reactants are present in the sample carrier stream and are added to the sample zone as a consequence of dispersion. The configuration is associated with the inception of flow injection analysis and is characteristic of the sequential injection analyser. Flow injection systems comprising two or more streams that converge to form the main carrier stream into which the sample is inserted [134] are also considered as single-line flow systems. 

Sequential injection systems were conceived [89] to simplify flow-based analytical procedures and enhance versatility and robustness for process monitoring. The confluence connections usually present in segmented flow and flow injection analysis are eliminated and different analytical applications can be implemented without the need for multiple manifold re-configuration. 

FIGURE 1.3 Schematic manifolds of typical flow injection analysis (FIA) systems (a) single line manifold, (b) multiline configuration RCl, RC2—reaction coils. (Adapted from Ruzicka, J., 2009, Tutorial on Flow Injection Analysis (4th ed.). From Beaker to Micro fluidics, www.flowinjection.com.)... 

Conversely, confluence flow injection systems rely on sample insertion into a chemically inert carrier stream and the required reagents are added by confluence. The configuration is characteristic of the segmented flow analyser. The carrier (or background) stream is a solution similar to the sample but without the chemical species under determination. Distilled water, soil extracting solution, ethanol and synthetic seawater are examples of chemically inert carrier streams for the analysis of natural waters, soil extracts, spirits and seawater, respectively. 

Another application of in situ analysis is the quality control of industrial processes. In general, the sample is taken from the process (batch or continuous) and directed towards the analytical path of the flow system a reagent aliquot is inserted into it (reagent injection flow injection configuration — see also 3.2.1). The sample volume extracted is usually minimal compared with the scale of the process. Alternatively, the process... 

Initial experiments have demonstrated the feasibility of flow manifolds having a stacked configuration for chemical analysis systems A substantial reduction in system size may be accomplished when micromachined silicon elements are employed Implementation of the concept of merging zones of sample and reagents and the valveless injection scheme result in more efficient consumption of reagents In order to benefit fully from the possible advantages of miniaturization, a carefril design of the components as well as the analysis methods is required... 

A schematic of a commercially available system that was conflgured in our laboratory for parallel analysis and purification is shown in Figure 11-9. This four-channel parallel LC/MS purification system consists of a binary HPLC system, an autosampler configured with four injection, a multichannel UV detector, a quadrupole mass spectrometer equipped with an MUX ion source which monitors four flow streams simultaneously, and four independently... 

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