Modified Capillary Electrophoresis for Highly Sensitive and Selective Detection of Hg2+ in Natural Water

A novel capillary with high sensitivity and selectivity for mercury ion detection based on modified nanosize silica has been designed and synthesized. The obtained modified capillary was applied to separate and determine mercury ion by capillary electrophoresis with a laser-induced fluorescence detector. The optimal experimental conditions were determined by evaluating various controlling factors: running buffer hexamine-HCl 15 mmol L-1, pH = 5.2, separation voltage 30 kV and temperature 25 degrees C. The modified capillary exhibited excellent sensitivity and selectivity for Hg2+ over other coexisting metal ions (K+, Ag+, Ca2+, Mg2+, Ba2+, Ni2+, Cd2+, Pb2+ and Zn2+ increased to 10000 times of Hg2+, Cu2+ increased to 5000 times) in aqueous solution, and was successfully applied to the determination of Hg2+ in natural water samples and displayed satisfactory results.