Measurement precision and accuracy of high artificial enrichment

Oversaturation of the Faraday cup amplifiers of isotope ratio mass spectrometers when using tracers that are highly enriched in heavier isotopes (up to 99.9%) remains a major bottleneck to obtaining high-precision measurements. The memory effect plays a key role in reducing tracer sample measurement precision and accuracy. Several sample preparation approaches are known to reduce memory effects and to improve tracer sample measurement precision. However, the potential benefits when using very high enrichment tracer samples (+1000 mUr) have not been tested.In this study, we test how specific sample positioning for measurements and frequent use of natural isotope abundance reference materials within the sequence affects the precision and accuracy of isotopic ratio analyses when using a Flash elemental analyser coupled to a DeltaFrequent use of natural isotope abundance materials and specific positioning increasedWe conclude that highly enriched tracer samples do not require dilution before analysis. Tracer sample precision can be improved by using a specific measurement order of expected isotope abundance and by the frequent use of natural abundance reference materials.