[Determination of heavy metals in infusion solutions using modern polarography methods]

The pharmacopoeial method of determination of heavy metals based on the formation of coloured sulphides, in comparison with instrumental methods, has relatively little sensitivity and does not provide selective determination of the individual ions. In order to determine some heavy metals in water for injection and infusion solutions, the authors employed the method of differential pulse polarography (DPP) and differential pulse anodic solvent voltammetry (DPASV) on the hanging mercury dropping (HMDE) with the use of the fast scan method (FSDPP). DPASV method proved to be particularly suitable; without any larger analytical problems the sensitivity of determination up to 8.10(-10) mol.1(-1) for copper, lead, cadmium and zinc ions was achieved. Bismuth and tin ions are also polarographically active, as well as nickel and chromium ions with the use of SPP. The medium of pH 4 achieved by adding potassium hydrogen-phthalate proved to be good. When there was an interfering effect of the access of chloride ions for copper determination, a strongly acid medium of hydrochloric acid 1 mol.1(-1) was used; an interfering effect of decomposition products of sugars on zinc determination was eliminated by performance at pH 7. Potentials of the peaks of the individual metals in various media are shown in Table I, the found values in Table II.