This is to compensate for possible degradation of the titrant solution. Complexometric titrations rely on the formation of a complex between the analyte and the titrant. What happens if some other species which reacts with the analyte (the titrant) is added? A plot of the current against volume of added titrant will be a straight line. In this experiment, the applied current is equivalent to a titrant. E is recorded at intervals as the titrant is added. Let A represent the titrant, and B the titrand. In practice, the use of EDTA as a titrant is well established. Thus the potentiometric titration involve measurement of E with the addition of titrant. The total volume of added titrant is then used to estimate the free acidity. Nickel can be titrated thermometrically using di-sodium dimethylglyoximate as titrant. Typical titrations require titrant and analyte to be in a liquid (solution) form. Sulfate may be rapidly and easily titrated thermometrically using standard solutions of Ba as titrant. The volume of titrant that reacted with the analyte is termed the "titration volume". Using a catalytically indicated endpoint, very low EDTA titrant concentrations can be used.