流动注射分析中试样分散的对流－扩散理论

Convection -Diffusion Theory of Sample Dispersion in Flow Injection Analysis System

用两种方法求解适合于单一平直管道且无化学反应的流动注射分析（ＦＩＡ）体系的对流－扩散方程，得到了描述塞状进样在管道中分散后的浓度分布公式，从而得到Ｆ曲线。讨论了反应管和采样管的内径和长度、流速和扩散系数对峰形和分散度的影响；采用数值法解出半峰宽与扩散系数的关系，提出了两种测定扩散系数的方法，为ＦＩＡ体系的设计和指示物质、操作条件的选择提供了理论依据．

Two methods were used to solve the convection-diffusion equation which appropriate to straight single-tube Flow Injection Analysis(FIA)system without chemical reaction,and the concentration distribution of the slug-injected sample after dispersing in the tube was obtained.F-Curve was thereby obtained.Effects of inner radius of tube,length ofreaction tube,length of sampling tube,flow rate and diffusion coefficient on peak shape anddispersion were discussed.The relationship between half peak width and diffusion coefficientwas solved by numerical method.Two methods to determine diffusion coefficient by FIA were suggested.This paper offered a theoretical guideline for design of FIA system,selection of indicator and operating condition.