Determination of Trace Copper and Lead in Water by FAAS Combined with SPE Using Dithiooxamide Modified Silica

Dithiooxamide modified silica gel was prepared and used as a absorbent in SPE. Under the conditions of pH 5.2 and the adsorption time of 40 min, the maximum static adsorption capacities of Cu2+ and Pb2+ obtained were 19.50, 29.39 mg·g-1, respectively. After being seperated and enriched by SPE, trace Cu2+ and Pb2+ in water were determined by AAS. Under optimum conditions, the linearity ranges of Cu2+ and Pb2+ were 1.0-100 μg·L-1 and 10-300 μg·L-1, respectively, with detection limits (3S/N) of 0.7 μg·L-1 and 5.0 μg·L-1, respectively. Recovery rates obtained by standard addition method were in the range of 97.6%-104%. The proposed method was applied to the analysis of standard reference material, giving results consistent with the certified values.