火焰原子吸收光谱法测定铅锌矿尾矿矿渣中镉和铬

Determination of cadmium and chromium in lead-zinc ore tailings slag by flame atomic absorption spectrometry

采用响应面法考察了火焰原子吸收光谱仪的几个工作参数间的相互作用和相互影响,对测定铅锌矿尾矿矿渣中Cd和Cr的工作条件进行了优化。采用Box-Behnken Design试验设计研究了灯电流、光谱通带、乙炔流量和燃烧器高度四个因素对铅锌矿尾矿矿渣中Cd和Cr吸光度的影响程度。用响应面法得出四个考察因素的最优工作参数如下:Cd,灯电流为1.02mA,光谱通带为0.26nm,乙炔流量为1 323.56mL/min,燃烧器高度为8.13mm;Cr,灯电流为1.65mA,光谱通带为0.36nm,乙炔流量为2 853.42mL/min,燃烧器高度为6.62mm。在火焰原子吸收光谱仪最优检测工作参数下,对铅锌矿尾矿矿渣样品中的Cd和Cr进行测定,Cd和Cr平均含量分别为6.9μg/g和42.5μg/g,加标回收率在96%～105%之间,RSD在0.39%～1.2%范围;对铅锌矿和铬铁矿标准物质进行测定,测定值与认定值一致,符合检测方法要求。

The interaction and mutual influence among several operating parameters of flame atomic absorption spectrometer were investigated through response surface method, and the working condi- tions for determination of Cd and Cr in lead zinc ore tailings slag were optimized. By Box-Behnken De- sign, the extent of influence for four factors including lamp current, spectral band width, acetylene flow rate and burner height on the absorbance of Cd and Cr in lead zinc ore tailings slag was discussed. The optimal operating parameters of the four factors derived through response surface method were as follows： lamp current of 1.02 mA, spectral band width of 0.26 nm, acetylene flow rate of 1 323.56 mL/min, and burner height of 8.13 mm for Cd; lamp current of 1.65 mA, spectral band width of 0.36 nm, acetylene flow rate of 2853.42 mL/min, and burner height of 6.62 mm for Cr. Under the optimal operating parameters of flame atomic absorption spectrometer, Cd and Cr in the lead zinc ore tailings slag samples were determined. The results indicated the average content of Cd and Cr was 6.9 μg/g and 42.5 μg/g respectively, the recoveries were among 96%-105%, and the relative standard de- viations （RSDs） were within the range of 0. 39% to 1.2%. For determination of lead zinc ore and chromite certified reference materials, the results were consistent with the certified values, which met the requirements for detection method.