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疏水性螯合物固相萃取-原子吸收光谱法测定海水中5种重金属

Determination of 5 Heavy Metals in Seawater by Atomic Absorption Spectrometry with Solid-phase Extraction of Hydrophobic Chelate

  • 摘要: 海水重金属的含量变化与分布特征受海洋中生物地球化学过程控制。海水重金属测定的难点在于海水盐度高且重金属含量低,需要进行分离、富集等样品前处理。常规前处理方法如溶剂萃取样品量大、操作繁琐,使用大量有机溶剂,对环境和操作者危害大;共沉淀法容易造成污染。本研究以吡咯烷基二硫代甲酸铵和二乙氨基二硫代甲酸钠为螯合剂,采用商品化的固相萃取柱,分离海水中的镉、铜、铅、镍和锌5种重金属,原子吸收光谱法测定其含量。结果表明:5种元素工作曲线的相关性较好(R>0.999),镉锌的线性范围分别为0~4 μg/L和0~100 μg/L,铅铜镍的线性范围为0~40 μg/L;检出限(μg/L)分别为0.02、2.6、0.06、0.18、0.3,方法精密度高(RSD < 5%),加标回收率为93.8%~104%。本方法利用疏水性作用的固相萃取技术,实现了海水分析的绿色样品前处理。

     

    Abstract: The concentration and distribution of heavy metals in seawater are controlled by biogeochemical processes in the ocean. It is difficult to analyze accurately the concentrations of heavy metals in seawater due to the high salinity of seawater and low concentrations of heavy metals. Separation and preconcentration processes are needed. Conventional pretreatment methods include solvent extraction and coprecipitation. During solvent extraction, large volumes of seawater samples and organic solvents are used, complicating the procedure and endangering the environment and operator. The coprecipitation method can readily cause contamination of the analytes. In this study, the concentrations of 5 heavy metals, Cd, Cu, Ni, Pb and Zn in seawater were determined by Atomic Absorption Spectrometry after solid phase extraction of hydrophobic chelate with ammonium pyrrolidine dithiocarbamate and sodium diethyldithiocarbmate as chelating agents. The results show that there is a good correlation (R>0.999) between the absorbance and concentration of Cd, Cu, Ni, Pb and Zn. The linear ranges of the working curve for Cd and Zn were 0-4 μg/L and 0-100 μg/L, respectively, whereas the linear ranges for Pb, Cu, and Ni were 0-40 μg/L. The detection limits (μg/L) of Cd, Zn, Pb, Cu and Ni were 0.02, 2.6, 0.06, 0.18 and 0.3, respectively. The precision and recovery were less than 5% and 93.8%-104%, respectively. This method utilizes the hydrophobic interaction of solid phase extraction technology to realize the green sample pretreatment of seawater analysis.

     

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