Metal ions are ubiquitous in the biosphere. In living organisms metalloprot
eins with specifically designed metal cores perform vital chemical processe
s. On the other hand, several heavy metals are detrimental to living organi
sms and nature has developed effective enzymatic detoxification systems whi
ch convert toxic metal ions to less toxic species. The nuclear spectroscopy
technique Time Differential Perturbed Angular Correlation (TDPAC) of gamma
-rays uses radioactive isotopes as nuclear probes in these metal cores to
obtain a better understanding of the structural and functional significance
of these metal cores by monitoring the nuclear quadrupole interaction of t
he TDPAC probe. Since this technique is based on the nuclear decay, it is a
lso applicable under physiological conditions, i.e., especially at picomola
r concentrations. For these studies an indispensable prerequisite is the pr
oduction of the TDPAC probes with highest possible specific activity and pu
rity as is done by the on-line mass separator ISOLDE at CERN in Geneva.