Inductively coupled plasma mass spectrometry (ICP-MS) procedures with isotope dilution were established for the accurate determination of trace Zn (in the level of 10−4 to 10−5 g g−1) in several tens of mg of geological and cosmochemical rock samples. Zinc was determined by 66Zn/67Zn and 68Zn/67Zn ratios with the use of an enriched isotope, i.e.67Zn. Among possible interferences for Zn isotopes (66Zn, 67Zn and 68Zn), molecular ions from ambient gases and sample solutions were found to be negligibly small, whereas doubly charged Ba ions (132Ba2+, 134Ba2+ and 136Ba2+) potentially interfered with the three Zn isotopes concerned. Either such interferences were eliminated by chemical separation in the matrix-separation ICP-MS procedure or they were mathematically corrected in the ICP-MS procedure without matrix separation. The three analytical procedure studies were evaluated in terms of analytical capability and data quality.
