Comparison of the Maximum Sensitivity of Different Flow Injection Manifold Configurations: Alternating Variable Search Optimization of the Iron(II)/1,10-Phenanthroline System

Three manifold configurations used in flow injection analysis were optimized for maximum sensitivity for the spectrophotometric determination of iron(II) by complexation with 1,10-phenanthroline. The parameters of flow rate(s), injected volume, manifold length and reagent concentration were studied for single, double, and reverse single line flow injection manifolds. All the manifolds produced maximum sensitivity when the dispersion coefficient (measured from the product profile) was less than 1.1. All the flow injection configurations were of comparable sensitivity, with that of the reverse configuration being slightly higher than those of the other two. The double line configuration gave the lowest detection limit (10 ng mL -1 ) because of the absence of refractive index peaks