we have run many experiments with Rb to optimize Sr interference correction and calibration approaches over the years with a NU Plasma HR and NP II, usually with a desolvation membrane for sample introduction. We have never had any problems related to Rb. Blanks usually go down with the usual rinse with diluted nitric acid, even with the desolvator, which is normally the source of memory, if there is any. Also, with other ICP-MS instruments (PerkinElmer, Agilent, Thermo), we never observed increased background.
Thus, I would not be worried to run Rb on the ICP-MS.
DI Dr.nat.techn. Irrgeher Johanna
Helmholtz Centre Geesthacht
Institute of Coastal Research
Department Marine Bioanalytical Chemistry
Max-Planck Straße 1
D-21502 Geesthacht, Germany
E-Mail: [log in to unmask]; [log in to unmask]