Influence of hydroxycarboxylic acids on the water solubility of various bismuth compounds
Heinemann, A.; Strugala, G.; Elsenhans, B.
Arzneimittel-Forschung 45(1): 48-51
1995
ISSN/ISBN: 0004-4172 PMID: 7893269 Document Number: 442677
In an equilibrium dialysis assay (bismuth being determined by atomic absorption spectrometry) a constant amount of bismuth (Bi. CAS 7440-69-9) (final maximum conc. 50 mu-mol Bi/l) was dialyzed against solutions with increasing concentrations of the chelators (0-25 mmol/l). At pH 5, 50 % of Bi(III) nitrate was soluble in solutions with 0. 3, 6.3, 13.4 and 14.6 mmol/l of edetic acid (EDTA), citric, tartaric and malic acid, respectively. At the highest concentration applied, lactic acid kept 7 % of bismuth in solution. Without any chelator, bismuth was found to be essentially insoluble (limit of detection: approx. 4 nmol Bi/l). A concentration-dependent increase in solubility was found also for the other bismuth compounds; the sequence of the solubilizing capacity of the chelators was the same as for Bi(III) nitrate. Lowering the pH to 3 generally increased and raising the pH to 7, decreased the solubility of bismuth.
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