Recent applications on isotope ratio measurements by ICP-MS and LA-ICP-MS on biological samples and single particles

Inductively coupled plasma mass spectrometry (ICP-MS) and laser ablation ICP-MS (LA-ICP-MS) have proved themselves to be powerful and sensitive inorganic mass spectrometric techniques for analysing stable and radioactive isotopes in different application fields because of their high sensitivity, low detection limits, good accuracy and precision. New applications of ICP-MS focus on tracer experiments and the development of isotope dilution techniques together with nanoflow injections for the analysis of small volumes of biological samples. Today, LA-ICP-MS is the method of choice for direct determination of metals, e.g., on protein bands in gels after the gel electrophoresis of protein mixtures. Tracer experiments using highly enriched Cu-65 were utilized in order to study the formation of metal-binding bovine serum proteins. A challenging task for LA-ICP-MS is its application as an imaging mass spectrometric technique for the production of isotope images (e.g., from thin sections of brain tissues stained with neodymium). In this paper, we demonstrate the application of imaging mass spectrometry on single particles (zircon and uranium oxide). Single Precambrian zircon crystals from the Baltic Shield were investigated with respect to isotope ratios using LA-ICP-MS for age dating. The U-Pb age was determined from the isochrone with (1.48 +/- 0.14) x 10(9) a. Using isotope ratio measurements on 10 nuclear uranium oxide single particles the U-235/U-238 isotope ratio was determined to be 0.032 +/- 0.004. This paper describes recent developments and applications of isotope ratio measurements by ICP-MS and LA-ICP-MS on biological samples and single particles. (c) 2007 Elsevier B.V. All rights reserved.