The AAS, ICP-MS and electrochemical determinations of zinc in selected pharmaceutical preparations.

Controlling of elements content in drugs is indispensable for drug quality evaluation. Zinc was selected for study because zinc contents in drugs span a wide range. Numerous multi-mineral preparations used and nutritional supplements to make up for the microelemental deficiencies in humans and animals, contain less than 0.001% zinc, i.e., trace amounts of zinc. On the other hand, external application drugs such as ointments and suppositories usually contain more than 0.1% of zinc. Zinc was determined out in Technilab's "Hemacort HC" ointments and suppositories, in Nattermann's "Dolovit Multimineral" tablets, and in Richter Pharma's "Minerasol" parenteral veterinary solution. These preparations were selected for investigation not only in view of differentiated zinc contents, but also because of the various drug forms and various procedures involved in sample preparation procedures. The tablets were dissolved with the aid of microwave energy, the ointment and suppositories were extracted, and the parenteral solution was diluted with water or with and aqueous 1% nitric acid. Atomic absorption spectrometry with graphite-tube (AAS), inductively coupled plasma mass spectrometry (ICP-MS), adsorptive stripping voltammetry (AdSV), square-wave voltammetry (SWV), and differential pulse polarography (DPP) were used for the determinations. Zinc was determined within concentration ranges of 20-40 ppb, 0.5-20 ppb, and 10-50 ppb by AAS, ICP-MS and AdSV, respectively. In the AAS and ICP-MS, zinc recoveries were contained within the limits of 101.8-114.2% and 111.0-114.2% respectively. The errors of determination (RSD) were 3.37-5.74% in AAS, 0.28-4.47% in ICP-MS and 0.19-2.50% in the electrochemical method.