Preconcentration of Ultra-trace Cadmium with Nanometer-size TiO2 Colloid and Determination by GFAAS

A novel method of ultra-trace Cd(Ⅱ) preconcentration with nanometer-size TiO2 colloid and determination by graphite furnace atomic adsorption spectrometry(GFAAS) with slurry sampling was first advanced in this paper. The adsorption efficiency of nanometer-size TiO2 colloid for ultra-trace Cd(Ⅱ) could reach above 96% in a short time when the pH value was between 5 and 6. Other problems were also studied, such as adsorption capacity, nanometer-size TiO2 colloid dosage, effect of coexistent ions. The detection limit(3σ) and the relative standard deviation (R.S.D) of this method were 4.46.10-3 μg/L and 1.30%(n=7), respectively. The method was successfully applied to the analysis of environmental samples with recoveries between 93.8%and 96.4%.