Evolution of the commutation concept associated with the development of flow analysis

Evolution of the commutation concept has lead to the proposal and developme nt of different generations of flow analyzers. Since the inception of the a ir-segmented flow systems till the availability of modern flow injection, s equential-injection and other flow-based analytical systems, a noteworthy i mprovement of the commutating devices has been noted. Multi-functional manifold is described as a polyvalent approach for methodo logy implementation in a flow analyzer. It permits the investigation of mix ing conditions under different flow patterns (unsegmented, segmented, monos egmented) with optional exploitation of the stopped-flow approach. For this purpose, spectrophotometric or turbidimetric measurements eventually affec ted by Schlieren noise were considered. Potentialities and limitations of t he manifold are discussed in relation with methods based on relatively fast or slow chemical reactions. As applications, phosphate and chloride determ inations in plant digests and natural waters were selected. The manifold is characterized by high versatility and may work in connectio n with different flow configurations. Development will certainly lead to si mple, versatile and miniaturized analyzers, able to run samples in a person alized fashion. In addition, random reagent selection, full automation, exp ansion of the analytical application range and increasing potentialities of the already existing methodologies are devised. (C) 1999 Elsevier Science B.V. All rights reserved.