title: Effect of water content in perchloric acid on the non-aqueous potentiometric titration of nitrogen-containing compounds.
abstract: In the United States Pharmacopeia (USP), 0.1 N perchloric acid in acetic acid volumetric solution (hereafter HClO4 VS) used for non-aqueous titration has specified a water content between 0.02 and 0.05%. Preparing this titrant with such a narrow range of water content is very time consuming, precludes the use of commercially available titrants, and, consequently, prompted an investigation to try and expand the range up to 0.5%. In this study, the titrimetric results obtained using HClO4 VS containing more water were very close to those obtained using the USP specified titrants. A maximum assay difference of 0.7% in the titrations of three selected nitrogen-containing compounds, clonidine hydrochloride, dipyridamole, and adenosine were observed. The titrimetric results obtained using these titrants were also precise with RSDs of not more than 0.4%. Therefore, a wider range of water content in HClO4 VS between 0.02 and 0.5% is suggested for the USP potentiometric titration of nitrogen-containing compounds.
authors.affiliation: Pharmaceutical Sciences Department, Fujisawa USA, Inc., Melrose Park, IL 60160, USA.
authors.forename: X S
authors.initials: XS
authors.lastname: Qi
authors.forename: R B
authors.initials: RB
authors.lastname: Miller
authors.forename: Y
authors.initials: Y
authors.lastname: Namiki
authors.forename: J
authors.initials: J
authors.lastname: Zhang
authors.forename: R
authors.initials: R
authors.lastname: Jacobus
mesh_terms: D007202:Indicators and Reagents; D008628:Mercury; D017672:Nitrogen Compounds / Q000032:analysis*; D010472:Perchlorates / Q000737:chemistry*; D011199:Potentiometry; D012996:Solutions; D014867:Water / Q000737:chemistry
chemical_list: D007202:Indicators and Reagents; D017672:Nitrogen Compounds; D010472:Perchlorates; D012996:Solutions; D014867:Water; D008628:Mercury; C029823:mercuric acetate