PubMed · 922243
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W M Heller. Infusions.. https://pubmed.ncbi.nlm.nih.gov/922243/
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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.
Three currently available pressure infusor devices, based on three different principles, were tested to see if the pressure reading on the infusor manometer corresponds to the pressure generated in the infusion system. Each device was tested in two ways. First, the pressure generated in the infusion system was measured when the infusor bag pressure was maintained at 300 mmHg while the infusion bag was emptied in aliquots of 50 ml. Second, the pressures in the infusor bag required to maintain a pressure of 300 mmHg were measured as the infusion bag was emptied stepwise. The results reveal surprisingly large discrepancies between the pressure registered on the infusor manometer and the actual pressure generated in the fluid, which are not due to manometer inaccuracy. The degree of discrepancy depends on the amount of fluid that remains in the infusion bag and, when the infusor manometer shows a pressure of 300 mmHg, pressure in the fluid can be as much as 170 mmHg above or 200 mmHg below this value. Furthermore, it was impossible to maintain a pressure of 300 mmHg in the infusion system using one of the devices despite the fact that 100 ml fluid remained. The clinical significance of these findings is discussed.
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