Development of a solid phase extraction method for the multielement determination of trace metals in natural waters including sea-water by FI-ICP-MS

Abstract

An automated solid phase extraction method by flow analysis on-line inductively coupled plasma mass spectrometry (FI-ICP-MS) for the determination of cobalt, chromium, nickel, cadmium, manganese, zinc, copper and lead in sea-water and other natural waters is described. The system is based on retention of the analytes onto a minicolumn packed with a chelating resin, 1,5-bis (2-pyridyl)-3-sulphophenyl methylene thiocarbonohydrazide immobilized on aminopropyl-controlled pore glass, placed in the injection valve of a simple flow manifold. The effects of chemical and flow variables were investigated and selected as a compromise between sensitivity and sampling frequency. So, the sample solutions (adjusted to pH 8.0±0.5) were passed through the column. After washing the column with water, the adsorbed metals were subsequently eluted into the plasma with 4% m/m nitric acid. Detection limits of the trace metals (180s sample loading time at a sample flow rate of 0.7mLmin−1; sampling frequency 8.6h−1) were 0.002μgL−1 for Co, 0.057μgL−1 for Cr, 0.117μgL−1 for Ni, 0.004μgL−1 for Cd, 0.210μgL−1 for Mn, 0.260μgL−1 for Zn, 0.030μgL−1 for Cu and 0.020μgL−1 for Pb, with enrichment factors between 2.2 and 6.8. The accuracy of the proposed method was checked with certified reference materials (CRMs) of sea-water SLEW 3, LGC6016 and CASS-5, river water SLRS-5 and fortified lake water TMDA-54.4. The results from the determination of these metals were in agreement with the certified values and recovery values ranged between 92.2 and 110.6%. The method was applied to the determination of these metal ions in sea-water samples collected in the Málaga Bay in order to realize a pilot study necessary to generate preliminary information on which to base a more detailed pollution study by heavy metals of the Bay.