Determination of trace metals in sea-water and the on-line removal of matrix interferences by flow injection with inductively coupled plasma mass spectrometric detection

Sea water buffered to pH 8 was transported onto a Dionex Metpac CC-1 microcolumn containing a macroporous iminodiacetate (IDA) chelating resin (theoretical column capacity 0.45 mequivalents) in a carrier stream (0.8 ml/min) of 0.01M-ammonium acetate buffer of pH 5.3. Matrix impurities, including chloride and Na ions were removed and trace metals bound to the column, were eluted with 2M-HNO₃ (0.8 ml/min) and analysed by ICP MS (experimental conditions described). Trace metal impurities were removed from the ammonium acetate buffer prior to analysis (procedure described). The analytical procedure was validated with standard sea water and estuarine water samples spiked with multi-element standards (Mn, Co, Cu, Zn and Pb). Calibration graphs were linear for 0.1-0.4 µg/l of the metals. RSD (n =5) for the elements was 2.3-6.9% for a standard open ocean sea water spiked with a 0.1 µg/l multi-element standard. Recoveries of Mn, Cu, Zn and Pb were 94-105%; high recoveries (137% and 131%) of Co were associated with the levels of this element in the reagents used for preconcentration and elution.