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×-2x+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.
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