Determination of metal ions in water and tea samples by flame-AAS after preconcentration using sorghum in nature form and chemically activated

Sorghum-agricultural waste in nature ( SAWN ) and chemically activated with phosphoric acid ( SAWAC ) was used as a solid phase extraction material for determination of cadmium, copper, manganese and lead ions in aqueous solutions by flame atomic absorption spectrometry ( FAAS ). The effect of pH, sample flow rate and volume, eluent type, volume and flow rate, and the effects of potentially interfering ions on the recovery of the analytes were investigated. Adsorption capacity of SAWN and SAWAC was determined by batch method under the optimized conditions. Adsorption capacity of SAWAC was found to be 9.53, 11.77, 11.64, and 15.01 mg/L for Cd, Cu, and Mn and Pb ions, respectively. The limit of detection ( LOD ) for the analytes was found in the range of 0.16–1.21 μg/L with a theoretical preconcentration factor of 50. The method was validated by analyzing certified material (GBW 07605-Tea) and the results were in a good agreement with the certified value. In addition, the proposed method was applied to the determination of analytes in tea and river water samples.