Determination of trace amount of silver by atomic-absorption-spectrometry-coupled flow injection on-line coprecipitation preconcentration using DDTC-copper as coprecipitate carrier

A flow injection on-line coprecipitation preconcentration system with diethyldithiocarbamate (DDTC) chelate of copper used as the coprecipitate carrier was coupled with flame atomic absorption spectrometry (FAAS) for the determination of trace silver. Silver was on-line coprecipitated with DDTC-Cu(II) in 0.5 mol.L-1 HCl, and the precipitate was collected in a knotted reactor. The precipitate was then dissolved by isobutyl methyl ketone and transported directly into the nebulizer-burner system of a flame atomic absorption spectrometer. A detection limit (3 sigma) of 0.6 mu g.L-1 was achieved for a loading period of 30 s, a relative standard derivation of 2.0% was obtained for 11 determinations of 20 mu g.L-1 Ag(I) Interference-free levels were 10 mg.L-1 for Cd2+, 50 mg.L-1 for Cu2+, 50 mg.L-1 for Mn2+, 25 mg.L-1 for Ni2+, 100 mg.L-1 for Pb2+, 50 mg.L-1 for Zn2+, 500 mg.L-1 for Fe3+, and 2000 mg.L-1 for Fe2+ reduced from Fe3+ by ascorbic acid. The developed method has been successfully applied to the determination of trace amount of silver in geological samples, (C) 1998 Academic Press.