Testing and Improving Interlaboratory Comparability of Tooth Enamel Carbonate Isotope Analyses

Summary

This is an abstract from the "SAA 2024: Individual Abstracts" session, at the 89th annual meeting of the Society for American Archaeology.

Carbon and oxygen isotope ratios of human tooth enamel carbonate are frequently used to reconstruct past diet, movement, and environmental conditions. Despite a long legacy of research, samples are prepared and analyzed using a remarkably broad range of protocols, and this methodological heterogeneity raises questions about the comparability of isotopic data across studies. We report a systematic comparison of isotope delta (𝛿) values for 10 “modern” faunal teeth (obtained from field recoveries) measured in two different laboratories. Our tests included comparisons of enamel powder subsamples that were chemically pretreated using commonly adopted protocols and subsamples that received no pretreatment. We also evaluated 𝛿 values generated with and without (1) standardizing the reaction temperature used during isotope ratio mass spectrometry and (2) baking the samples and vials to remove moisture before analysis. The results showed that 𝛿 values from the two laboratories were systematically different when samples were chemically pretreated, but that differences were smaller or negligible for untreated samples. Standardization of reaction temperature and baking also improved comparability. We suggest that the widely adopted practice of oxidant and acid pretreatment of enamel samples is largely unnecessary and may compromise the accuracy of stable isotope analyses.

This Resource is Part of the Following Collections

• SAA 2024: Individual Abstracts   •
• Society for American Archaeology 89th Annual Meeting, New Orleans, LA (2024)

Keywords

Record Identifiers

Abstract Id(s): 38890.0