动态三磁场塞曼效应背景校正石墨炉原子吸收法测定土壤中镉
Determination of Cadmium in Soil by Graphite Furnace Atomic Absorption Spectrometry with Dynamic Tri-magnetic Field Zeeman Effect Background Correction
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摘要:
目的 建立动态三磁场塞曼效应背景校正石墨炉原子吸收法测定土壤中镉含量的分析方法。
方 法 土壤样品经风干除杂,研磨过筛,微波消解后,以磷酸氢二铵为基体改进剂,优化塞曼分裂条件,动态三磁场背景校正模式进行测定。
结果 以2.0 μg/L为浓度分界点,仪器自动给出各个浓度在二磁场和三磁场模式下的光密度值,其中0.0~2.0 μg/L浓度范围采用二磁场背景校正模式,标准曲线方程为ŷ=3.98×10-2
x +5.05×10-3,r =0.996 8,特征浓度0.11(μg/L)/1%y ;在2.0~50.0 μg/L浓度范围采用三磁场背景校正模式,标准曲线方程为ŷ=(-9.7×10-5+1.42×10-2x )/(1+2.36×10-2x ),r =0.998 1,特征浓度0.31(μg/L)/1%y ,回收率在90.0%~103.0%之间,相对标准偏差(RSD)在3.2%~4.2%之间。结论 本方法操作简便,准确度、精密度好,扩展了镉测定的线性范围,满足浓度不一的土壤中镉的测定,适用于环境调查土壤中镉含量测定。
Abstract:Objective To establish a method for determining cadmium in soil by graphite furnace atomic absorption spectrometry (GFAAS) with dynamic tri-magnetic field Zeeman effect background correction.
Method Air-dried, ground, and sieved soil samples were assisted with microwave digestion using diammonium hydrogen phosphate as matrix modifier. Under optimized conditions of Zeeman splitting, cadmium concentration was measured in dynamic tri-magnetic field background correction mode.
Result Using 2.0 μg/L as cut-off point, GFAAS instrument displayed absorbance values at each concentration in bi-magnetic filed and tri-magnetic field modes. When the concentrations ranged from 0.0 μg/L to 2.0 μg/L, the bimagnetic filed background correction mode was used with the correlation equation of ŷ=3.98×-2
x +5.05×10-3,r =0.996 8, and the characteristic concentration was 0.11(μg/L)/1%y . When the concentrations ranged from 2.0 μg/L to 50.0 μg/L, the tri-magnetic field background correction mode was used with the correlation equation of ŷ=(-9.7×10-5+1.42×10-2x )/(1+2.36×10-2x ),r =0.998 1, and the characteristic concentration was 0.31(μg/L)/1%y . The recovery of standard addition was within 90.0%-103.0%, and the relative standard deviation (RSD ) was within 3.2%-4.2%.Conclusion This simple, accurate, and precise method can effectively extend the linear range of cadmium concentration detected; therefore, it is suitable for the determination of cadmium in soil.