Abstract: 2-Mercaptobenzothiazole-modified silica gel was used for the flow injection online pre-concentration-separation and determination of silver by flame atomic absorption spectrometry. Two types of manifold, with one or two columns, were adopted. Silver ion was selectively adsorbed from 0.05 to 6 M HNO3 solution and was readily desorbed by thiourea solution The ions coexisting with Ag(I) exhibit virtually no interference in the determination with the exception of Cl-. An Ag(I) concentration ≥1 ppb could be determined reliably if a long pre-concentration time was used. The sample throughput was 60 h-1 using the two-column manifold with a pre-concentration time of 60 s. Ag in a geological sample, a copper metal sample and a lead nitrate sample was determined satisfactorily.