Application of 2-mercaptobenzothiazole-modified silica gel to on-line preconcentration and separation of silver for its atomic absorption spectrometric determination

Abstract

2-Mercaptobenzothiazole-modified silica gel was used for the flow injection on-line preconcentration–separation and determination of silver by flame atomic absorption spectrometry. Two types of manifold, with one or two columns, were adopted. The results showed that Ag⁺ was selectively adsorbed from 0.05 to 6 M HNO₃ solution and was readily desorbed by thiourea solution. The ions co-existing with Ag⁺ exhibit virtually no interference in the determination with the exception of Cl^–. An Ag⁺ concentration as low as 1 ppb could be determined reliably if a long preconcentration time was used. The sample throughput was 60 h^–1 using the two-column manifold with a preconcentration time of 60 s. Silver in a geological sample, a copper metal sample and a lead nitrate sample was determined satisfactorily.