Indicator argentimetric titrations

In variants based on the determination of alcoholyzable halogen, chlorine and bromine have been determined69 by solvolysing the sample in a sealed tube with sodium butoxide. The resulting chloride or bromide was determined by argentimetric titration, with visual, or preferably potentiometric, indication of the end-point. 

Different electrochemical methods have been worked out to indicate the endpoint of argentimetric titrations. They can be used for the analysis of chloride as well as for the other halides. Their application is especially advantageous in mechanized or automated titrators. 

Iodide ions can be determined quite well with argentimetric titrations. The Volhard method, electrometric endpoint indications, and adsorption indicators work well. The Mohr endpoint indication, however, does not give good results because of the adsorption of the chromate on the silver iodide precipitate. The presence of chloride and bromide ions disturbs the argentimeric iodide determination. 

Issa et al. [9] used various metal ions for the volumetric determination of mefenamic acid. Mefenamic acid was precipitated from its neutral alcoholic solution by a standard solution of either silver nitrate, mercurous acetate, or potassium aluminum sulfate. In the argentimetric procedure, residual Ag(I) was titrated with standard NH4SCN. With Hg(OAc)2 or potash alum, the residual metal was determined by adding EDTA and conducting back titration of excess of EDTA with standard Pb(N03)2 using xylenol orange indicator. The applied methods were used for the determination in bulk drug substance, and in its formulations. 

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