Chapter 40 - International Stable Isotope Reference Materials

Abstract

This chapter discusses the most important international stable isotope reference materials that define six scales for the elements hydrogen, carbon, nitrogen, oxygen and sulfur. The availability and the proper use of suitable reference materials is one of the basic preconditions to ensure the comparability of stable isotope ratio measurements as performed by different laboratories. Comments are given on isotope reference materials for the elements lithium, boron and chlorine. Certain basic requirements for the used reference materials have to be fulfilled The problem of a proper terminology for reference materials and terms proposed for general use with the intention to achieve better consistency is discussed in the chapter. The available reference materials are intended to calibrate local laboratory standards that are prepared by the individual laboratories. The reference materials are not intended to be used themselves for quality control purposes. The rules that should be applied for an optimal calibration using available reference materials, regardless of the element under consideration are listed. The recent situation, demands and future trends for new isotope reference materials are also discussed.