Study on the determination of cobalt, nickel, copper, zinc and vanadium in environmental samples by a rapid high-performance liquid chromatography

A new method for the simultaneous determination of five transition metal ions in water and food by rapid high-performance liquid chromatography was developed. The cobalt, nickel, copper, zinc and vanadium ions were pre-column derivatized with 2-(2-quinolinylazo)-4-methyl-1,3-dihydroxidebenzene (QAMDHB) to form Colored chelates, then the Co-QAMDHB, Ni-QAMDHB, Cu-QAMDHB, Zn-QAMDHB and V-QAMDHB chelates were enriched by solid phase extraction with a C-18 cartridge. The enrichment factor of 50 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 (4.6 x 50 mm, 1.8 mu m) with 68% methanol (containing 0.1% of acetic acid and 0.1% of CTMAB) as mobile phase at a flow rate of 2.0 mL/min and detected with a photodiode array detector from 450-600 nm. The Co-QAMDHB, Ni-QAMDHB, Cu-QAMDHB, Zn-QAMDHB and V-QAMDHB chelates were separated completely within 2.0 min. The detection limits of cobalt, nickel, copper, zinc and vanadium are 2 ng/L, 1.5 ng/L, 2 ng/L, 3 ng/L, and 3 ng/L, respectively, in the original samples. This method was applied to the determination of the five transition metal ions in water and food samples with good results.