Figure 8.19
A series of ICP-MS specta showing the interference from
some polyatomic argon species, and the improvement
brought about by the HEX de-clustering technology.distinguish between lead from paint or water pipes on the one hand and petrol anti-knock agents on the
other (Figure 8.20). In geochemistry isotopic ratios can be used to indicate the date of crystallization of
rocks. The ratio is fixed at the time of crystallization, but can change subsequently as a result of
radioactive decay. With a measurement of isotopic ratios, and a knowledge of the radioactive half-life,
the original date of crystallization can be estimated. Ratios such as^87 Rb:^87 Sr,^147 Sm:^144 Nd,^207 Pb:^204 Pb,
and^206 Pb:^204 Pb are used.
Tracer studies in which chemically similar species are studied on the basis of containing a radioisotope
are discussed in Chapter 10. It is fairly obvious that, with detection techniques readily available for the
measurement of non-radioactive isotopes, the principle can be extended to non-radioactive systems.
Where in vivo studies are concerned there are clear safety reasons for so doing. Although some progress
is being made in this direction, it is