Determination of trace silver in environmental samples by room temperature ionic liquid-based preconcentration and flame atomic absorption spectrometry

We report on a new method for preconcentration of silver ion at trace level in environmental samples, and its subsequent determination by flame atomic absorption spectrometry (FAAS). The room temperature ionic liquid (RTIL) 1-butyl-3-methylimidazolium hexafuorophosphate and the chelator 5-(4-dimethylaminobenzylidene)-rhodanine were used for extraction. Ag(I) was back-extracted from the organic phase into thiosulfate solution and then determined via FAAS. The effects of pH, concentration of chelating agent, extraction time and temperature, amounts of ionic liquid, ionic strength and potentially interfering ions were studied. Under optimized conditions, the enhancement factor is 30 was achieved. The detection limit (3 sigma) is 0.28 ng mL(-1), and the relative standard deviation is 4.1% for 7 replicate determinations at 5 ng mL(-1) of Ag(I). The method was validated by analysis of certified reference materials and applied to the determination of Ag(I) in environmental samples with satisfactory results.