Titrimetric determination of gold in some pharmaceutical preparations

Abstract

Two titrimetric methods based on derivative potentiometry and catalytic controlled-current potentiometry were developed to determine the content of some gold compounds as gold in pharmaceutical preparations using potassium iodide solution as titrant. A negatively polarised glassy carbon indicator electrode, and the CeIV - AsIII system in the presence of sulphuric acid as an indicator reaction, served to monitor the catalytic titrations. The same glassy carbon electrode was also used in the derivative potentiometric titrations. Particular attention was paid to sample decomposition. Contents of gold of about 30 μg ml-1 were determined with a relative standard deviation of less than 1.4%. The results showed satisfactory agreement with those of comparative methods.