DETERMINATION OF SILVER(I) BY AN ASSOCIATION COMPLEX-FORMATION BETWEEN SILVER-ADENINE AND EOSIN

A sensitive and selective spectrophotometric determination of silver(I) based on an association complex between silver-adenine and eosin was established. The apparent molar absorptivity of the complex, without solvent extraction, was 1.1x10(5) dm3 mol-1 cm-1 at 560 nm. No metal ion interfered in an equimolar ratio of silver (I) among the metal ions examined. The method was applied to assays of silver in silver solder and silver protein: the results were in good agreement with those obtained by ICP-AES. The sensitivity could be further enhanced about 5-10 times over that of spectrophotometry with the third-derivative spectrophotometry and/or the fluorescence quenching method. Thermodynamic parameters (DELTAG=-6.34 kcal mol-1, DELTAH=-28.17 kcal mol-1 and DELTAS=-72.73 cal mol-1 K-1) and the binding parameters (n=0.98 and K=4. 10X10(4) M-1 at 27-degrees-C) suggest that colored complex formed in this reaction system is an association complex between silver-adenine and eosin.