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Capillary electrophoresis (CE) was coupled to ICPMS in order to combine the good performance of this separation technique with the high sensitivity of the ICPMS for the analysis of plutonium and neptunium oxidation states. The combination of a fused-silica capillary with a MicroMist AR 30-I-FM02 nebulizer and a Cinnabar small-volume cyclonic spray chamber yielded the best separation results. With this setup, it was possible to separate a model element mixture containing neptunium (NpO2(+)), uranium (UO2(2+)), lanthanum (La3+), and thorium (Th4+) in 1 M acetic acid. The same conditions were also suitable for the separation of various oxidation states of plutonium and neptunium in different aqueous samples. All separations were obtained within less than 15 min. A detection limit of 50 ppb identical with 2 x 10(-7) M (3-fold standard deviation of a blank) was achieved. To prove the negligible disturbance of the plutonium and neptunium redox equilibria during the CE separations, plutonium and neptunium speciation by CE-ICPMS in acidic solutions was compared with the results of UV/visible absorption spectroscopy and was found to be in good agreement. The CE-ICPMS system was also applied to study the reduction of Pu(VI) in a humic acid-containing groundwater at different pH values.

SummaryExperiments with different oxidation states of Pu in GoHy-532 groundwater under reducing conditions reveal that Pu(VI) and Pu(V) are reduced rapidly to Pu(IV) at pH 7. The half-life of the redox reactions Pu(VI)/(V) and Pu(V)/(IV) are in the range of minutes. The rates of both reduction reactions decrease with decreasing pH values. A portion of the Pu(IV) is not stable in the same groundwater and is reduced slowly to Pu(III) in the range of weeks. Ultrafiltration experiments show Pu to be totally bound to the humic substances in the groundwater. At Pu concentrations of 10

Adsorption / Transactinides / Element 112 / ThermochromatographySummary. Two experiments aiming at the chemical investigation of element 112 produced in the heavy ion induced nuclear fusion reaction of 48 Ca with 238 U were performed at the Gesellschaft für Schwerionenforschung (GSI), Darmstadt, Germany. Both experiments were designed to determine the adsorption enthalpy of element 112 on a gold surface using a thermochromatography setup. The temperature range covered in the thermochromatography experiments allowed the adsorption of Hg at about 35 • C and of Rn at about −180 • C. Reports from the Flerov Laboratory for Nuclear Reactions (FLNR), Dubna, Russia claim production of a 5-min spontaneous fission (SF) activity assigned to 283 112 for the 238 U( 48 Ca,3n) 283 112 reaction. Hence, Experiment I was designed to detect spontaneously fissioning (SF) isotopes of element 112 with half-lives (t 1/2 ) longer than about 20 s. 11 high-energy events were detected. 7 events exhibit a deposition pattern resembling a chromatographic peak in the vicinity of Rn deposition. However, the energy of the events observed in Experiment I was lower than expected for a SF-decay of 283 112. Therefore, these events could not be unambiguously attributed to the decay of 283 112. In contradiction with earlier publications newer reports from FLNR Dubna claim that 283 112 decays by α-particle emission (E α = 9.5 MeV) with t 1/2 = 4 s followed by a SF-decay of 279 Ds (t 1/2 = 0.2 s). Therefore, Experiment II was designed to be sensitive to both claimed decay properties of 283 112. However, during

Element 108 / Hassium / Volatile HsO 4 / In-situ production / Adsorption on hydroxide / CALLISTO Summary. Hassium, element 108, was produced in the fusion reaction between 26 Mg and 248 Cm. The hassium recoils were oxidized in-situ to a highly volatile oxide, presumably HsO 4 , and were transported in a mixture of He and O 2 to a deposition and detection system. The latter consisted of 16 silicon PIN-photodiodes facing a layer of NaOH, which served, in the presence of a certain partial pressure of water in the transport gas, as reactive surface for the deposition of the volatile tetroxides. Six correlated α-decay chains of Hs were detected in the first 5 detectors centred around detection position 3. In analogy to OsO 4 , which forms Na 2 [OsO 4 (OH) 2 ], an osmate(VIII), with aqueous NaOH, HsO 4 presumably was deposited as Na 2 [HsO 4 (OH) 2 ], a hassate(VIII).