Appendix VIII A. Non-aqueous Titration
Method I
Dissolve the prescribed quantity of the substance being examined in a suitable volume of anhydrous acetic acid previously neutralised using the indicator specified in the monograph, warming and cooling if necessary, or prepare a solution as directed. When the substance is a salt of hydrochloric or hydrobromic acid, add 15 mL of mercury(ii) acetate solution before neutralising the solvent, unless otherwise directed in the monograph. Titrate with 0.1m perchloric acid VS to the colour change of the indicator that corresponds to the maximum absolute value of dE/dV (where E is the electromotive force and V is the volume of titrant) in a potentiometric titration, Appendix VIII B, of the substance being examined. The indicator specified in the monograph is also used for the neutralisation of the mercury(ii) acetate solution and the standardisation of the titrant.
When the temperature (t2) of the titrant at the time of the assay differs from the temperature (t1) of the titrant when it was standardised, multiply the volume of the titrant required by [1+0.0011(t1 - t2)] and calculate the result of the assay from the corrected volume.
Carry out a blank titration when necessary.
Method II
The titrant, solvent and, where necessary, the indicator to be used are stated in the monograph.
Protect the solution and titrant from atmospheric carbon dioxide and moisture throughout the determination.
Dissolve the substance being examined in a suitable volume of the solvent previously neutralised to the indicator, warming and cooling if necessary, or prepare a solution as directed. Titrate to the colour change of the indicator that corresponds to the maximum absolute value of dE/dV (where E is the electromotive force and V is the volume of titrant) in a potentiometric titration, Appendix VIII B, of the substance under examination. The titrant is standardised using the same solvent and indicator as specified for the substance.
Carry out a blank titration when necessary.