Determination of copper, nickel, cobalt, silver, lead, cadmium, and mercury ions in water by solid-phase extraction and the RP-HPLC with UV-Vis detection

A new method for the simultaneous determination of seven heavy metal ions in water by solid-phase extraction and reversed-phase high-performance liquid chromatography (RP-HPLC) was developed. The copper, nickel, cobalt, silver, lead, cadmium, and mercury ions were pre-column derivatized with tetra(m-aminophenyl) porphyrin (Tm-APP) to form colored chelates. The metal-Tm-APP chelates in 100 mL of sample were preconcentrated to I mL by solid-phase extraction with a C-18 cartridge; an enrichment factor of 100 was achieved. The chelates were separated on a Waters XterraRP(18) column by gradient elution. with methanol (containing 0.05 mol L-1 pyrrolidine-acetic acid buffer salt, pH 10.0) and acetone (containing 0.05 mol L-1 pyrrolidine-acetic acid buffer salt, pH 10.0) as mobile phase at a flow rate of 1.0 mL min(-1) and detected with a photodiode array detector. The detection limits of copper, cobalt, nickel, silver, lead, cadmium, and mercury are 2, 2, 3, 4, 3, 3, and 3 ng L-1, respectively, in the original sample. The method was also applied to the determination of these metals in water with good results.