Advances in isotope ratio mass spectrometry and required isotope reference materials

Abstract

The article gives a condensed version of the keynote lecture held at the International Mass Spectrometry Conference 2012 in Kyoto. Starting with some examples for isotope research the key requirements for metrologically valid procedures enabling traceable and comparable isotope data are discussed. Of course multi-collector mass spectrometers are required which offer sufficiently high isotope ratio precision for the intended research work. Following this, corrections for mass fractionation/discrimination, validation of the analytical procedure including chemical sample preparation and complete uncertainty budgets are the most important issues for obtaining a metrologically valid procedure for isotope ratio determination. Only the application of such metrologically valid procedures enables the generation of traceable and comparable isotope data. To realize this suitable isotope and/or δ-reference materials are required, which currently are not sufficiently available for most isotope systems. Boron is given as an example, for which the situation regarding isotope and δ-reference materials is excellent. Boron may therefore serve as prototype for other isotope systems.

Keywords: comparability; delta reference materials; isotope reference materials; mass discrimination; mass fractionation; measurement uncertainty; synthetic isotope mixtures; traceability.

Fig. 1. Schematic principle of the synthetic isotope mixture approach for correcting instrumental mass fractionation/discrimination by full calibration of the mass spectrometer. Copied with permission. Copyright BAM 2012.

Fig. 2. Current situation for boron regarding isotope reference materials. Copied with permission from ref. . Copyright Springer Verlag, 2012.