Highly selective determination of inorganic mercury(II) after preconcentration with Hg(II)-imprinted diazoaminobenzene-vinylpyridine copolymers

Hg(II) imprinted and non-imprinted copolymers were prepared by metal ion imprinted polymer (MIIP) technique. The copolymers were obtained by copolymerizing mercury chloride (or without it), diazoaminobenzene (DAAB) and vinylpyridine (VP) using ethyleneglycoldimethacrylate (EGDMA) as cross-linker in the presence of 2,2′-azobisisobutryonitrile as initiator. The separation and preconcentration characteristics of the copolymers for Hg(II) were investigated by batch and column procedures. The results demonstrated that the Hg(II) imprinted copolymers had higher adsorption capacity with the value of 205 μmol g−1 of dry copolymer, about 3.5 times of and good selectivity for Hg(II) compare to non-imprinted copolymers (58.6 μmol g−1 of dry copolymer). The distribution ratio (D) values of the Hg(II) imprinted copolymers increased for Hg(II) with respect to both D values of Zn(II), Cu(II), Cd(II), CH3HgCl, CH3CH2HgCl and non-imprinted copolymer. The relatively selective factor (αr) values of Hg(II)/Cu(II), Hg(II)/Zn(II), Hg(II)/Cd(II), Hg(II)/CH3HgCl and Hg(II)/CH3CH2HgCl are 45.5, 63.5, 55.1, 49.6 and 84.0, respectively. The tolerance limit for other electrolytes such as NaCl, KBr, KI, NaNO3, Na3PO4, Na2SO4 and Mg(NO3)2 is also greatly improved with the values of 10-100-fold of the non-imprinted copolymer. The Hg(II) imprinted copolymers can be used at least 20 times with recoveries no less than 95%. Based on the packed columns with Hg(II) imprinted copolymers, a highly selective solid-phase extraction (SPE) and preconcentration method for Hg(II) from dilute aqueous solution was developed. The MIIP-SPE preconcentration procedure showed a linear calibration curve within concentration range from 0.13 to 25 μg l−1. The detection limit and quantification limit were 0.05 and 0.13 μg l−1 (3σ) for cold vapor atomic absorption spectrometry (CVAAS). The relative standard deviation of the eleven replicate determinations was 2.4% for the determination of 1.0 μg of Hg(II) in 100 ml water sample. Determination of Hg(II) in certified river sediment sample (GBW 08603) demonstrated that the column was good enough for Hg(II) determination in matrixes containing components with similar chemical property such as Cu(II), Zn(II), Cd(II), CH3HgCl and CH3CH2HgCl.