Redox titration. Footage of the stages in a redox titration analysis. The first stage is the mixing of the two reagents in a conical flask. This is followed by the use of a burette to add a reagent containing an indicator (purple). The flask is swirled to mix the reagents. The endpoint of the reaction is reached when a permanent purple colour is present in the flask. A redox titration is one where a redox reaction occurs between the analyte and titrant. This titration is permanganate ions (MnO4-, purple) in the burette reacting with ferrous ions (Fe2+) in the conical flask.