Simultaneous measurement of picomolar zirconium, hafnium, niobium and tantalum in seawater using commercially available chelating resin and subsequent ICP-MS determination

In the present study, a novel and simple method to measure picomolar to subpicomolar dissolved Zr, Hf, Nb and Ta in seawater is described. The method provides a preconcentration step (250 times) by mini-column filled with a commercially available chelating resin. The proposed method has a lower blank and better precision than previous methods. Furthermore, using a more dilute hydrofluoric acid as eluent, the new method quantitatively recovered (97-102%) all of these elements spiked in seawater. Determination of Zr, Hf, Nb and Ta in North Pacific seawater at 100 m depth were 39, 0.14, 2.4 and 0.03 pmol/kg, respectively. These results are consistent with previous reports. Finally, we applied the proposed method to seawater samples taken from the North Atlantic Ocean during the U.S. GEOTRACES expedition and report the results for the first time in this paper.