纳米SiO_2分离富集-火焰原子吸收法测定水中痕量银

研究了纳米SiO_2分离富集-火焰原子吸收法测定水中痕量银的新方法.考察了溶液pH、吸附时间、洗脱条件和干扰离子等因素对Ag~+分离富集的影响,确定了纳米SiO_2对Ag~+吸附的最佳条件.结果表明:在pH 4.1时,纳米SiO_2能定量吸附银,吸附在纳米SiO_2上的Ag~+可用0.5 mol/L HCl+0.5 mol/L硫脲定量洗脱.该法对银的检出限为0.77 ng/mL(3σ,n=11);线性范围为0.005～1.5μg/mL,对0.5μg/mL的Ag~+标液进行7次测定,RSD为3.6%,回收率在94.0%～101.5%之间;方法可用于环境水样中痕量银的测定.

Determination of trace silver in water by flame atomic adsorption spectrometry after separation/preconcentration with nanometer SiO_2

A new method for the determination of trace Ag based on nanometer SiO_2 separation/preconcentration and flame atomic adsorption spectrometric (FAAS) determination was studied. The optimum conditions for adsorption were studied in detail including the effect of pH on adsorption ratio, adsorption time, elution conditions and effect of inter-ference ions. It was fond that Ag~+ could be adsorbed quantitatively on nannmeter SiO_2 at pH 4.1 and the adsorbed sil-ver could be eluted with 0.5 mol/L HCl and 0.5 mol/L thiourea. A linear response of silver was obtained in the range from 0.005 to 1.5 μg/mL with the limit of detection of 0.77 ng/mL (3σ, n = 11). The relative standard deviation un-der the optimum conditions was 3.6% (n = 7, p = 0.5 μg/mL) and the recoveries of silver were 94.0%～101.5%. The method has been applied to the determination of trace silver in environmental water samples with satisfactory re-sults.