  Techniques have been developed to measure the isotopic composition of trace
elements from matrices predominantly consisting of interfering isotopes. These
techniques have been applied to measuring mass-independent fractionation of
molybdenum in ancient zircon samples due to nuclear decays. Improvements to the
digestion of large zircon samples and the ion exchange chemistry required to
separate trace molybdenum from zirconium silicate are presented. The efficacy
of TEVA ion exchange resin as a replacement for anion resin to improve
separation efficiency and chemistry blank was studied. An algorithm was
established to improve background, interference and mass bias corrections for
the data analysis of Mo by multi-collector inductively coupled plasma mass
spectrometry (MC-ICPMS). This enabled the isotopic composition measurement of
$<$50 ng of Mo recovered from 500 mg ZrSiO$_4$ by reducing the Zr content by
$>$9 orders of magnitude while retaining 63% of the Mo. With 5 ng of Zr still
remaining, novel data analysis techniques enabled $<$0.1 permil precision on
each Mo isotope. The relevance of this technique to extracting other atomic
species is also discussed.
