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

An equation relating the peak separation (Δteq), 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 Δteq 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.