Determination of trace metals in sea-water by inductively coupled plasma mass spectrometry interfaced with an ion chromatographic separation system: effectiveness of nitrilotriacetate chelating resin as the column stationary phase for preconcentration and elimination of matrix effects

Abstract

Trace metals in sea-water were determined by ion chromatography (IC)–inductively coupled plasma mass spectrometry (ICP-MS). A nitrilotriacetate (NTA)-type chelating resin was applied to the separation and enrichment of the analyte metal ions. Transition metals and rare earth elements except Mn were retained on the NTA resin column whereas alkali and alkaline earth metals were eluted from the column by elution with 0.5 mM nitric acid. The NTA resin can simplify the procedure for matrix elimination and enrichment of analyte metals since mineral acids can be used as eluents. A linear calibration and repeatability of the signal intensity of ICP-MS were obtained in the determination of trace metals at the <1 µg l–1 level. This method was applied to the analysis of the Open Ocean Sea-Water Reference Material NASS-4. The analytical values (for Co, Ni, Cu, Zn, No, Cd, Sb, Pb and U) were in good agreement with the certified values. By using ammonium acetate buffer solution (pH 5.28) in the preconcentration step, Mn was also retained quantitatively on NTA resin, and the analytical values of the metals (Mn, Co, Ni, Cu, Zn, No, Cd, Sb, Pb and U) contained in NASS-4 were in good agreement with the certified values.