A Simple ICP-MS Method for the Determination of Rhenium in Seawater and Its Concentration in Tokyo Bay

In order to determine Re in seawater samples by inductively coupled plasma mass spectrometry, a simple separation method has been applied. An extraction chromatographic resin (TEVA resin, Eichrom Ind. Inc.) was employed to separate Re from sample matrices and trace elements that cause isobaric interferences during ICP-MS measurements. Indeed, more than 98% of W was removed with this resin separation step; thus, there was no WH+ interference on the Re isotopes. Overall recovery of Re from seawater spiked with enriched 185Re tracer was 96.8+/-2.9%. The instrumental detection limit by ICP-MS was 0.2 pg mL-1; therefore, 100 mL of seawater sample, which usually contains Re in low pg mL-1 levels, provides good signals for an accurate determination. The Re concentration in Tokyo Bay from the surface to the bottom showed almost constant Re concentrations, with an average of 7.1 pg/g for November and 7.3 pg/g for December 2002. For the samples collected in January 2003, a different vertical distribution trend from the last two months was observed, though the values were within the reported range