Determination of trace elements in natural water samples by air-segmented flow-injection/ICP-MS after preconcentration with a chitosan-based chelating resin

Ultratrace elements in natural water samples were determined simultaneously by air-segmented flow-injection/inductively coupled plasma-mass spectrometry (SFI/ICP-MS). A small volume of the sample solutions (80 mu l) was introduced into a nebulizer by an air-segmented flow-injection (SFI) system, and a maximum of fifteen elements were measured during each run. A chitosan-based chelating resin containing functional groups of iminodiacetate was used to separate and enrich analyte metal ions. A 50-fold preconcentration using 50 mi of sample solutions was achieved by the proposed method, where 1 mi of 0.1 M nitric acid was added to residues after drying the chelating column effluent. At pH 6, several heavy metals (Fe, Ni, Co, Cu, Zn, Ag, Cd, Pb and U) and rare earth elements (REEs) were quantitatively retained on the chelating resin column, whereas alkali and alkaline earth metals were eluted from the column by rinsing with 5 mi of a 0.2 M ammonium acetate solution. Metals adsorbed on the chelating resin column were recovered by elution with 10 mi of 1 M nitric acid. The proposed method was applied to the determination of trace elements in several natural water samples, such as river water and mineral drinking water.