On-line solid-phase chelation for the determination of eight metals in environmental waters by inductively coupled plasma mass spectrometry

Abstract

A low-pressure method for the on-line preconcentration of analytes and elimination of matrix elements prior to determination by inductively coupled plasma mass spectrometry (ICP-MS) is described. The method reduces the concentrations of matrix elements in samples to levels that do not interfere with the determination of the first row transition elements at trace levels. The method also reduces biases caused by differences between samples and standards by delivering the analytes to the ICP-MS instrument in a consistent nitric acid matrix. A commercially available low-pressure sample manipulation system was used to perform solid-phase chelation on an iminodiacetate column. The effectiveness of the method is demonstrated for the determination of Cd, Co, Cu, Mn, Ni, Pb, U and Zn in the certified reference materials CASS-2, Near Shore Sea-water; NASS-4, Open Ocean Sea-water; and the Standard Reference Material 1643b, Trace Elements in Water. The volume of sample preconcentrated was varied in order to optimize the analyte signal. The detection limits for 10 ml samples ranged from 0.8 ng l–1 for Co to 40 ng l—1 for Cu and Zn.