双硫腙修饰纳米TiO_2分离富集石墨炉原子吸收光谱法测定水样中痕量金属离子

Determination of Trace Metal Ions in Water by Graphite Furnace Atomic Absorption Spectrometry after Separation and Preconcentration with Dithizone-modified Nanometer TiO_2

建立了双硫腙修饰纳米TiO2分离富集-石墨炉原子吸收光谱法测定水样中痕量镉、铬和铅的新方法,优化了纳米TiO2-双硫腙对试样中这3种痕量物质的吸附和解吸条件。结果表明,在pH 5.0时,镉、铬和铅可被定量吸附,静态饱和吸附容量分别为13.3、5.5、21.8 mg/g。吸附的各种金属离子可用5 mL 0.1mol/L的硝酸完全洗脱。该方法对Cd2+、Cr3+和Pb2+的检出限(3σ,n=11)分别为0.18、0.51、1.92 ng/L,相对标准偏差分别为2.8%、2.3%和1.0%,加标回收率为96%～101%。该方法已成功应用于环境水样中镉、铬和铅的测定。

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.