Studying the possibility of quantification of a metal-containing medicinal substance in the presence of metal impurities using bismuth subsalicylate as an example

Abstract

I n t r o d u c t i o n . The analysis of metals in pharmaceutical practice uses both for the quantification of an active ingredient and for assessment of elemental impurities. For metal-containing drugs, the analytical methods must be specific and free from the interference of elemental impurities.
A i m . To study the influence of elemental impurities on the quantification of the pharmaceutical substance bismuth subsalicylate.
M a t e r i a l s  a n d  m e t h o d s . As a test sample the active pharmaceutical substance bismuth subsalicylate was used obtained by two different ways. Standard samples of elemental impurities of copper, lead and silver were prepared in concentrations with the maximum impurity content according to the European Pharmacopoeia. The analysis was carried out by stripping voltammetry.
R e s u l t s . The addition of solutions of elemental impurities of copper, lead and silver, either separately or as a mixture of all three solutions, does not cause the appearance of a signal on the voltammogram corresponding to the bismuth peak. When quantifying the pharmaceutical substance bismuth subsalicylate and comparing the peak height values, the ratio of the indicators turns out to be equal or close to 100%.
C o n c l u s i o n . The presence of elemental impurities of copper, lead and silver does not interfere with the quantification of the pharmaceutical substance bismuth subsalicylate by stripping voltammetry.