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 i on 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 obt ained by ICP-AES. The sensitivity could be further enhanced about 5-10 times over that of spectrophotometry with the third-derivative spectr ophotometry and/or the fluorescence quenching method. Thermodynamic pa rameters (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. 10X 10(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.