New supplemental activator for lead isotope analysis using TIMS

Abstract

We have devised a new supplementary activator for lead isotope measurements performed using thermal ionization mass spectrometry (TIMS). The activator consisted of a mixture of 250 ppm Ge and 500 ppm Re and was used with normal colloidal silica. This new substance shows excellent performance in terms of enhancing the ion beam intensity. The supplementary activator yielded 3.5-4.5 × 10-11 A 208 Pb for 10 ng Pb, 1.5-2.5 × 10-11 A for 5 ng Pb, and ~1.5 × 10-11 A for 2.5 ng Pb samples, indicating that the new activator was superior to those currently in use. This improvement should be applicable to samples with low Pb content, for example, in environmental tracer studies and Pb-Pb chronology studies.

Evaluation of colloidal silicagels for lead isotopic measurements using thermal ionisation mass spectrometry

“…Our results indicate no noticeable dependence of ionisation efficiency on silicagel particle size, inconsistent with previous studies. 3,5,13 Note however that the previously suggested dependency is based on experiments using silicagels which vary not only in particle size, but also have different solvents and impurities. By contrast, our test was performed on a series of gels from the same company using the same solvent, allowing a more rigorous evaluation of the particle size effect.…”

“…Miyazaki et al 4 focussed on producing a silicagel with a small particle size, since this was suggested to increase the ionisation efficiency. 3 Nohda et al 5 searched for supplementary materials to increase the signal intensity and prolong the lifetime of the ion beam. Ge and Re were added to colloidal silicagel, which enhanced the ion beam for samples larger than 2.5 ng of Pb.…”

Atomic spectrometry update. Advances in atomic spectrometry and related techniques

“…The addition of 250 ppm Ge and 500 ppm Re with colloidal silica was used to enhance the ion beam intensity for IRA of Pb using TIMS, 217 while methods have been developed for IRA of K (TIMS) 218 and Mg. 219 There have been some new developments in sample introduction methods. A novel sample cone, the jet cone, has been tested with MC-ICP-MS for IRA of Hf and Pb at 'sub-ng' levels, with RSD for Pb isotope amount ratios ranging between 0.08% and 0.36% depending on isotopic abundance and concentration.…”