On-line Solid Phase Extraction of Nickel, Copper, and Cadmium Using a Newly Synthesized Polyamine Silica Gel-loaded Mini-column for Flame Atomic Absorption Spectrometric Determination

摘要

In this study, polyamine (pentaethylene hexamine) functionalized silica gel (PA-SG) was prepared as a novel sorbent material for on-line preconcentration of Cd(II), Cu(II), and Ni(II) from complex matrices. The PA-SG was characterized by means of elemental analysis and FT-IR spectroscopic techniques. The effective parameters for on-line preconcentration and separation of Cd(II), Cu(II), Ni(II）， and FAAS detection were optimized by investigating the effects of sample pH, type, and concentration of eluent, flow rate of sample and eluent, loop volume, and matrix ions. The linear range of the proposed method was betweenl0-200 μg L~(-1) for each element, with enrichment factors of 39.9, 30.4, and 43.6 and detection limits of 0.19, 0.73, and 0.91 μg L~(-1) for Cd(II)， Cu(II), and Ni(II), respectively, by loading 5.0 mL of sample solution. The precision of the method (evaluated as the relative standard deviation obtained after analyzing 11 samples with three replicates each) was determined as 3.2, 2.4, and 4.0% for 20 μg L~(-1) of Cd(II), 0.1 mg L~(-1) of Cu(II) and Ni(II), respectively, by loading 5.0 mL of sample solution. The sorption capacities of PA-SG were 41.4, 33.1, and 23.7 mg for Cd(II), Cu(II), and Ni(II) per gram of resin, respectively. The accuracy of the proposed on-line preconcentration procedure was evaluated by analyzing reference materials CTA-VTL-2 Virginia Tobacco Leaves and NWTM-15.2 Water - Trace Elements. Application of the proposed procedure was successfully accomplished for the analysis of natural water and food samples.