DETERMINATION OF TRACE AND PLATINUM-GROUP ELEMENTS IN HIGH IONIC-STRENGTH VOLCANIC FLUIDS BY SECTOR-FIELD INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRY (ICP-MS)

The accurate measurement of ultra-trace concentrations of rare metals and platinum group elements in volcanic fluids is complicated by inter ferences, complex matrices, and preferential element partitioning. We analyzed condensed, high-temperature magmatic fluids collected from Ku dryavy volcano (Kurile Islands, Russia) for Be, B, Rb, Sr, Mo, Ru, Rh, Pd, Cd, W, Re, Pt, Pb, Bi, and U using ICP-MS. The samples had three different matrices: 5 mol L-1 sodium hydroxide (NaOH, pH = 11), gas co ndensates of sulfuric acid (H2SO4, pH = 0), and solid elemental sulfur . Interferences and suppression/enhancement effects were investigated using standards in concentrated NaOH and H2SO4 solutions to determine adequate dilution for sample analyses, which then required very low le vels of element detection (< 1 mu g L-1 for most elements). Depending on the field sampling technique of volcanic gas vents, our results sho w significant differences in concentrations of some trace elements due to the precipitation of solid sulfur during gas condensation and vari ations in element volatility as a function of temperature.