Study on the determination of lead, cadmium, mercury, nickel and zinc by a rapid column high-performance liquid chromatography

Abstract

A new method for the simultaneous determination of five heavy metal ions in water, food and human hair by a rapid column high-performance liquid chromatography was developed. The lead, cadmium, mercury, nickel and zinc ions were pre-column derivatized with 2-(2-quinolinylazo)-4-methyl-1,3-dihydroxidebenzene (QAMDHB) to form colored chelates. Then the Pb-QAMDHB, Cd-QAMDHB, Hg-QAMDHB, Ni-QAMDHB and Zn-QAMDHB chelates were enriched by solid phase extraction with C18 cartridge. The enrichment factor of 100 was achieved by eluting the retained chelates from the cartridge with tetrahydrofuran (THF). These chelates were separated on a ZORBAX Stable Bound rapid analysis column (4.6X50 mm, 1.8 µm) with 68% methanol (containing 0.05 mol L-1 of pH 8.5 pyrrolidine-acetic acid buffer solution and 0.01 mol L-1 of CTMAB) as mobile phase at a flow rate of 2.0 mL min-1 using a photodiode array detector from 450-600 nm. The Pb-QAMDHB, Cd-QAMDHB, Hg-QAMDHB, Ni-QAMDHB and Zn-QAMDHB chelates were separated completely within 2.0 min. The detection limits of lead, cadmium, mercury, nickel and zinc are 1.2 ng L-1, 1.0 ng L-1, 0.8 ng L-1, 1.6 ng L-1 and 1.9 ng L-1, respectively in the original samples. This method was applied to the determination of these five heavy metal ions with good results.