Abstract: The inter-relationships of axial and radial dispersion with FIA operating parameters are critically examined and discussed. Using a computer-simulation, the relationship between axial dispersion and analyte residence times is clarified, and a model of axial dispersion free from contributing diffusional effects is presented.

Abstract: In published articles of the authors [11,13], there are five major qualitative equations on dispersion of sample zone injected into the flow-injection analysis (FIA) system. The five equations contain five coefficients and 10 exponents. This article gives a detailed description of the correlations between these coefficients and exponents in equations on theory of FIA dispersion by means of mathematical derivations and experimental evident. It has been discovered that if a coefficient and two exponents in either of five qualitative equations can be evaluated, the coefficients and exponents in another four qualitative equations can also be solved. Moreover, the mathematical method has also been established for finding the coefficient and exponents in one of the five equations. In addition, a study has been conducted on how to make these qualitative equations change into the five quantitative equations. This article has reported also two new concepts of axial dispersion degree (AD, AD = Sv,z/Sv = t/t) and intensity of radial dispersion (Jf, Jf = D/AD = SvC0/Sv,zCmax = tC0/tCmax) on the sample plug. AD and Jf can be applied not only for FIA but also for ion, gas, and liquid chromatographies as well as chemical engineering to evaluate axial and radial dispersions of injected materials. Correlations among AD, Jf, t, Qc, Lr, Sv, and D have been clarified, and qualitative equations related to AD and Jf were also deduced.

Abstract: This article presents two new parameters of axial dispersion degree (AD) and intensity of radial dispersion (Jf) for describing sample dispersion in flow-injection analysis systems (FIA) and presents their definition equations. AD and Jf not only can be applied for FIA but also for ion, gas, and liquid chromatographies as well as chemical engineering to evaluate axial and radial dispersions of injected materials. Correlation among AD, Jf, Sv, residence time (t), flow rate (Qc), reactor length (L, and dispersion coefficient (D) has been clarified. Qualitative equations related to AD and Jf have been deduced, and some implications of the equations are discussed. Through computer regression calculations with two sets of experimental data obtained from ZCFIA method by Chinese and Japanese FI analyzers, it was concluded that values of coefficients and exponents in these qualitative equations are not identical for different FIA instruments. These qualitative equations are well suitable for predicting and assessing variation tends and correlations of AD or Jf with Qc, L, t, Sv, and D, as well as for optimizing operation conditions in various flow systems.