Selective extraction and one-drop flame atomic absorption spectrometric determination of trace amounts of silver in highly-pure copper and lead

After the dissolution of copper and lead in sulfuric or nitric acid, silver was selectively extracted as a ternary silver-1,2-bis(ethylthio) ethane-picrate complex into a small volume of chloroform at pH 1.0-1.5, leaving copper and lead in an aqueous solution without a masking agent. Direct nebulization of 50 mu l of the chloroform extract into a fuel-lean air-acetylene flame gave a sensitive signal height without background correction from chloroform. The present method was successfully applied in the determination of silver in copper and highly-pure copper and lead metals.