Has anyone had issues either with Rb memory effects or cup poisoning from running Rb on TIMS or ICP?
We are discussing among our research group about running spiked Rb for Rb-Sr geochronology in our new Nu Plasma 3D MC-ICP-MS. We had such horrific experiences with memory effects with our Isoprobe MC-ICP-MS over the years that we are a little hesitant to move forward without evidence that it will not be a problem. Several folks in our group have expressed concerns that residual spiked Rb in the machine could interfere with the 87Rb correction for subsequent 87Sr analyses as the correction requires the assumption of a natural Rb isotope ratio to make the correction. Others are concerned with the ease of Rb ionization such that introducing Rb into the mass spec would "poison the cups" and produce phantom signals as the Rb re-ionizes during subsequent analyses. Has anyone experienced either of these problems or others from running spiked Rb in a modern TIMS or MC-ICP-MS? We are looking for observations allay our concerns.
As folks have (and still do) run Rb on both TIMS and ICP, I am sending this to both plasmachem and TIMS listservers.
Dr. Staci Loewy
Isotope Geochemist and
MC-ICP-MS Laboratory Manager
The University of Texas at Austin
Department of Geological Sciences
2275 Speedway, Stop C9000
Austin, TX 78712-1722
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