Determination of Ag and Cd in soil and sediment samples by Graphite Furnace Atomic Absorption Spectrometry (GFAAS)

Abstract

An extensive study has been made for the determination of silver (Ag) and cadmium (Cd) in soil and sediment samples using different decomposition procedures. A simple and rapid method has been developed for the accurate determination of Ag and Cd at ppb levels by graphite furnace atomic absorption spectrometry (GFAAS). In the present study, -200 mesh size samples were digested in a 100-mL glass beaker using 1:1 HNO3 for measurement of Ag and Cd by GFAAS. A bulk calibration standard of 20 ppb of Ag and 10 ppb of Cd was used for the measurement of silver and cadmium, respectively. The method was proposed for the determination of Ag and Cd in soil and sediment samples collected according to the guidelines of the National Geochemical Mapping (NGCM) program and is being followed by the Geological Survey of India with an objective for Geochemical Mapping. The precision of the proposed method was investigated by analyzing 10 soil and sediment samples, and the estimated value of the RSD (%) was found to be < 10%. The efficiency of the method was also compared by analyzing 10 international soil and sediment reference samples. Very good agreement and excellent precision were observed for the certified values. The limit of quantitation (10σ) achieved for Ag was 5.0 ng/g and for Cd it was 2.0 ng/g, with a recovery of 95-103%.