assay by titrimetry issue

[aniket1706]

Dear All,
This is related to Etodolac assay by titrimetry. In EP/USP monograph, potentiometric titration is given vs. 0.1 M tetrabutyl ammonium hydroxide in methanol/toluene. We are getting results on higher side varying between 110-115%.Normality calculated potentiometrically for the solution in triplicate is consistent. Electrode bein used for the titration is Metrohm 6.0229.100(pH electrode LiCl sat.in EThanol). The same titration carried out vs. 0.1M sodium hydroxide using pH electrode is giving consistent results. Has anybody experienced this kind of issue in the titration . Pl. guide.

[Markus Laeubli, Metrohm]

Dear aniket1706

For any support I would need more detailled information:

How did you determine the titer of TBAOH and sodium hydroxide (the same substance, same batch)?
What is the solvent of the titration?
Wich titration method do you use?
Do you have any electronic recors of the titration e.g. from tiamo?

Do not hesitate to contact me by e-mail (lae@metrohm.com).