Chapter 6 - Mass Spectrometric Techniques for the Determination of Lithium Isotopic Composition in Geological Material

Abstract

This chapter discusses the mass spectrometric techniques for the determination of Lithium isotopic composition in geological material. The method for high precision lithium isotope measurement is developed to analyze lithium in geological samples with a better standard deviation. It has produced a significant database for the reservoirs of the Earth, which show a span of 60%-70% in lithium isotopic composition. The isotopic systematics is valuable for understanding a wide range of geological processes, such as, oceanic crust alteration, hydrothermal activities, sediment-water interaction, arc magma genesis, and subsurface brine evolution. The element lithium has two stable isotopes are 6Li and 7Li. The cosmic abundance of lithium isotopes reflects primordial nucleosynthesis, galactic cosmic-ray spallation, and destruction processes. The modern mass spectrometric methods in the chronological order of their development include chemical preparation, thermal ionization mass spectrometry, and inductively coupled plasma mass spectrometry. The method based on the measurement of the analysis of diborate ions is obsolete because of inferior analytical sensitivity and precision, and laborious sample preparation. These methods are capable of measuring nanogram quantities of lithium thus providing the analytical capability for a wide range of geological materials.