Marine Chemistry of Zirconium, Hafnium, Niobium and Tantalum

Here, we present the first simultaneous preconcentration and determination of ultratrace (pmol/kg level) Zr, Hf, Nb, Ta and W in seawater, both in the form of dissolved and aciddissolvable species. 8-Hydroxyquinoline (8HQ) bonded covalently to a vinyl polymer resin, TSK-8HQ, was used in a chelating adsorbent column to concentrate the metals. The greatest advantage of this resin is its endurance to 5M HF, since this is an effective eluent for all five metals. The analytes were successfully concentrated from 250 mL seawater with a 50-fold concentration factor through the column extraction and evaporation. The detection limit was 0.009–0.15 pmol/kg. The procedure blank determined using ultra pure water as a sample was 0.005–0.37 pmol/kg. The five metals were quantitatively recovered from seawater with good precision (2–4%). The effect of sample pH, sample flow rate, eluent composition and sample pretreatment were carefully studied. This method was applied to seawater