矿床地球化学国家重点实验室知识库

The advent of multiple collector–inductively coupled plasma–mass
spectrometry (MC-ICP-MS) has made the high-precision determination
of Ge isotopes possible, which leads to the widespread application of
Ge isotopes in earth, ocean, and cosmochemistry fields. This paper
reviews the history of Ge isotope analysis, chemical dissolution and
purification, and mass spectrometry measurements. Concentrated
HNO3 is sufficient to dissolve nearly all types of samples and HF is also
involved for Si-rich samples. Low-temperature ashing prior to
dissolution is an alternative way to preconcentrate Ge in organic-rich
samples. For different matrices, Ge isotopes can be determined by
MC-ICP-MS coupled with a traditional nebulizer system or hydride
generation system after two-step separation, one step cation/
anion-exchange separation, or Mg/Fe co-precipitation protocols.
Ion-exchange column methods are suitable for samples with elevated
matrix and Ge content such as sulfides, iron oxides, silicate rocks, and
coals, whereas Mg or Fe coprecipitation methods are particularly
suitable for all kinds of water. Hydride generation systems are
improved over traditional nebulizer system due to the smaller sample
quantity and fewer matrix-related interferences. Sample-standard
bracketing, double spike, and external Ga isotope normalization are
used to mass bias correction and yield consistent results. Analytical
methods involving Ge-poor samples and Ge isotope analyses based on
different Ge species or specific Ge compound in natural environment
will be important prospects in the further study. For further
applications of Ge isotopes in mineral deposits such as sulfide and
iron oxide deposits, sulfides, and iron oxides reference materials should
be developed in the future.