A novel flow injection technique: all injection analysis.

Water quality control has become extremely important from industrial and environmental view points. Flow injection analysis (FIA) has been increasingly recognized as a valuable tool for such a monitoring system.1 However, some problems exist when FIA is used for a monitoring process. The most important problem is the consumption of large amounts of reagents and carrier solutions during continuous monitoring. Especially, when one needs to measure the sample absorbance at definite intervals, the amount of waste fluid and the consumption of reagents would increase further in a conventional FIA system. Thus, the authors have developed a novel flow injection technique in which all reagent solutions are injected into a reaction coil and all solutions are circulated for a definite time. By this circulating process, the amount of consumption of the reagents is extremely eliminated, even in intermittent measurements. The proposed system can be used for various analytical reaction systems without rearranging the construction of the FIA assembly. We refer to this flow injection technique as an “all injection analysis (AIA)”. In this paper, spectrophotometric determinations of iron(II), vanadium(IV) and copper(II) using the proposed system are described.