¹⁸O/¹⁶O and D/H ratio determinations for small amounts of water

Abstract

This paper describes an improved procedure for D/H and ¹⁸O/¹⁶O ratio analyses presented originally by Kishima and Sakai (1980). A sealed glass tube for the isotope exchange equilibration between water and CO₂ gas was employed instead of a conventional container with a greased stopcock. The use of the sealed tube enabled us to handle 5 ∼ 6μmol of water for accurate and precise δ¹⁸O measurement, with precision of 0.42‰ (1 σ_n-1). However, for precise δD measurement more than 40μmol of water was required.