Applications involving the iodide ion: I. A new potentiometric method for the micro- and semimicrodetermination of silver. Analysis of binary and ternary mixtures

Abstract

A new method is given for the accurate micro- and semimicrodetermination of silver involving precipitation of silver as the sparingly soluble silver iodide and back titration of excess iodide with standard mercuric solution using the silver amalgam as indicator electrode. Amounts of silver ranging from 30 milligrams down to 6.5 micrograms were determined with fair accuracy. Binary mixtures with copper were successfully analyzed. Ternary mixtures have been analyzed by aid of the additional volumetric methods using potassium cyanide as masking agent. The minimum amount of silver was determined with fair accuracy and precision in presence of a cluster of cations of Cu(II), Ba, Ca, Sr, Zn, Co(II), Ni(II), Cr(III), Cd, In, and Mg amounting in total to 22 milligrams. The same amount was determined with requisite accuracy in presence of 56 milligrams of Cu(II).