Influence of hydroxycarboxylic acids on the water solubility of various bismuth compounds.
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 mumol 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.
Heinemann
A
A
Walther Straub-Institut für Pharmakologie und Toxikologie, Ludwig-Maximilians-Universität, Munich, Fed. Rep. of Germany.
Strugala
G
G
Elsenhans
B
B
D001729:Bismuth / Q000737:chemistry*; D002614:Chelating Agents / Q000737:chemistry; D004492:Edetic Acid / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D006880:Hydroxy Acids / Q000737:chemistry*; D012995:Solubility; D013054:Spectrophotometry, Atomic; D014867:Water
D002614:Chelating Agents; D006880:Hydroxy Acids; D014867:Water; D004492:Edetic Acid; D001729:Bismuth