Determination of readily oxidised compounds by flow injection analysis and redox potential detection
Redox potential detection has been applied to the determination of reducing agents injected into a non-segmented stream of cerium(IV) solution. By dispersion the plug of injected sample was mixed with the reagent and the consequent redox potential shift, determined by the ratio of cerium(IV) to cerium(III), was detected by a platinum or graphite electrode with suitably placed indicator and reference electrodes. The flow-rate of the reagent stream was about 0.7–1.0 ml min–1. With 0.3-ml samples, well defined peaks were obtained. Millimolar or even weaker solutions of iron(II) and ascorbic acid were analysed with good reproducibility, the sample rate being about 45–60 per hour.