Analytical information from doublet peaks in flow injection analysis. Part I. Basic equation and applications to flow injection titrations

Abstract

An equation relating the peak separation (Δt_eq), between the doublet peak obtained when the reaction product of a flow injection titration is monitored, to all the basic operational variables was derived on the basis of the well stirred mixing chamber model. These variables consisted of the flow-rate, the volume injected, the volume of the mixing chamber and the concentrations of the reagent and the injection sample. The equation was tested for the predicted variation of Δt_eq with these variables for a system containing real mixing chambers but using slug injection. The reactants were copper(II) and EDTA and the product was monitored with a UV detector. Good agreement was obtained. The use of a gradient tube was demonstrated to give a good calibration for OH^– over the range 5 × 10^–5–5 M. A comparison of the doublet peak method with potentiometric methods was made.