| A new method was proposed for the determination of trace cadmium,chromium and lead by graphite furnace atomic absorption spectrometry(GFAAS) after preconcentration with dithizone-modified nanometer titanium dioxide(TiO2-DZ).The conditions of adsorbing and desorbing of nanometer TiO2-DZ for Cd2+,Cr3+and Pb2+ was optimized.The results indicated that the three metals could be quantitatively preconcentrated on the nanometer material at pH 5.0 and the static adsorption capacity of Cd,Cr and Pb were 13.3,5.5 and 21.8 mg/g,respectively.The preconcentrated metal ions could be completely eluted with 5 mL 0.1 mol/L HNO3.Under the optimum conditions,the detection limits (3σ，n=11) for Cd2+,Cr3+and Pb2+ were 0.18,0.51 and 1.92 ng/L,respectively,and the relative standard deviations were 2.8%,2.3% and 1.0%,respectively.The spiked recoveries ranged from 96% to 101%.The proposed method was successfully applied in the determination of trace cadmium,chromium and lead in natural water samples with satisfactory results. |