Spectrophotometric determination of trace amounts of silver with 5-[4-(2-methyl-3-hydroxy-5-hydroxymethyl)pyridylene]rhodanine

Abstract

The synthesis of 5-[4-(2-methyl-3-hydroxy-5-hydroxymethyl)pyridylene]rhodanine (PYR), its characteristics, its reactions with various noble metal ions and its application to the selective determination of silver are described. PYR reacts with silver to form a red complex (metal to ligand ratio 1 : 2) having an absorption maximum at 530 nm in aqueous solution containing 8%V/V of dimethylformamide at pH 8.2 (bicine-NaOH buffer solution). The molar absorptivity is 1.5 × 10⁴ l mol^–1 cm^–1 and the relative error for 3 µg ml^–1 of silver (11 replicates) is 0.85%.

The application of the proposed method to the determination of silver in drugs, silver pre-concentrate and galena is also described.