Abstract

The chemical equilibrium of the ternary complex ion associate of the complex anion AuCl4
- and the ion – pairing
reagent 1- (3, 5-diamino-6-chloropyrazinecarboxyl) guanidine hydrochloride monohydrate, DPG+.Cl- extracted
from aqueous solutions of pH 5-6 onto 4-methyl pentan-2-one was demonstrated. The extraction constants (Kex,
KD and ß) of the chemical equilibrium and the structure of the produced associate were determined. The results
have indicated that, the formation of the complex ion associate of the chemical structure DPG+.AuCl4
- and the
extraction mechanism does not involve solvation of the ion associate by the amine and/or water molecules in the
organic phase. Beer's law was obeyed in the range 0.01 -2.5 ?g mL-1gold (III) in the aqueous solution. The
method was applied successfully for the analysis of gold (I) after oxidation to gold (III). The method was also
applied for the analysis of gold (I& III) at trace concentrations in industrial wastewater samples. Gold (III) ions
at trace level in one liter aqueous solution was concentrated in 10.0 mL by the developed extraction system so an
enrichment factor of 100 was achieved. The time taken for the separation and determination of gold ions was in
the range of 3-5 min.

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