The production of ultra-high purity single isotopes or tailored isotope mixtures by ICP-MS

We report the development and testing of a collector arrangement for quadrupole inductively coupled plasma mass spectrometry (ICP-MS) that for the first time has been used to isolate small quantities of highly enriched (>99.99%) single isotopes, with deposition rates >10 ng h^-1. The collector assembly replaces the standard instrument detector allowing for implantation with simultaneous monitoring of the incident ion current. Even under zero bias implant conditions, low energy (<10 eV) ion collection efficiency was observed to be very high 99%. ¹⁵¹Eu ion currents of 0.1-0.5 nA were collected on a simple, planar foil without resorting to any type of cup configuration. Recovery of the enriched isotope from such foils is much simpler than from a more complex cup configuration. High rejection of adjacent mass isotopes was demonstrated by selectively implanting ¹⁶⁷Er, then using laser ablation ICP-MS imaging to confirm the absence of any co-implanted ¹⁶⁶Er or ¹⁶⁸Er. The important analytical possibilities of this new approach to isotope ratio measurement, tracer purification, and radiation measurements are discussed.