Flame atomic absorption spectrometric determination of silver in geological materials using a flow-injection system with on-line preconcentration by coprecipitation with diethyldithiocarbamate

Abstract

Trace amounts of silver in geological samples were determined by flame atomic absorption spectrometry. The analyte was preconcentrated and separated from the bulk of the matrix by on-line coprecipitation with the iron(II)-diethyldithiocarbamate complex in the presence of 1,10-phenanthroline in a flow-injection system. The precipitate was collected in a knotted reactor without using a filter. The precipitate was dissolved in isobutyl methyl ketone and introduced directly into the nebulizer-burner system of an atomic absorption spectrometer. 1,10-Phenanthroline was added to the sample solution to mask large concentrations of iron(II). The tolerance of the method for iron was thus increased to 4 g 1 −1. An enhancement factor of 26 and a concentration efficiency of 28 min −1 were obtained for a coprecipitation time of 45 s, resulting in a sampling frequency of 62 h −1. The detection limit (3σ) in the sample solution of 0.5 μg 1 −1. The relative standard deviation at the 30 μg 1 −1 level was 2.1%. The analytical results obtained for geological reference materials were in good agreement with the certified values.