MATHEMATICAL-MODELING OF FLOW-INJECTION SYSTEMS

Analysis of the great variety of now-injection (FI) manifolds used in analytical practice nowadays has shown that most of them can be decomposed into two basic now configurations, i.e., the single-line and the conjugated two-line system. The former system has one influent and one effluent stream through which it can contact with the environment. The conduit walls are totally impermeable. The most distinctive characteristic of a conjugated two-line system is the existence of a now-through section with two separate streams (e.g., donor and acceptor) which exchange matter continuously along a common semipermeable interface (e.g., membrane). It can be concluded that two of the cornerstones in the modelling of FI manifolds are the successful mathematical description of the two basic now systems mentioned above. Numerous mathematical models of FI systems employing ideas from different scientific areas (e.g., statistics, chemical engineering, artificial intelligence, chromatography) have been developed so far. It should be pointed out that the majority of them describe only single-line FI systems. A classification of all these models based on the main principles on which they are built, is proposed. The models have been compared with respect to their predictive power, the complexity of their mathematical treatment, and the requirements for computation time when applied to single-line and conjugated two-line FI systems. It is concluded that the axially dispersed plug now model deserves special attention because it offers an acceptable compromise between the conflicting requirements for maximal possible mathematical simplicity and maximal possible precision. It can be used as the basis for an unified approach to the modelling of FI systems.