Generation of two new radiocarbon standards for compound-specific radiocarbon analyses of fatty acids from bog butter finds

Emmanuelle J A Casanova, Timothy D J Knowles, Isabella Mulhall, Maeve Sikora, Jessica Smyth, Richard P Evershed

Research output: Contribution to journalArticle (Academic Journal)peer-review

Abstract

The analysis of processing standards alongside samples for quality assurance in radiocarbon analyses is critical. Ideally, these standards should be similar both in nature and age to unknown samples. A new compound-specific approach was developed at the University of Bristol for dating pottery vessels using palmitic and stearic fatty acids extracted from within the clay matrix and isolated by preparative capillary gas chromatography. Obtaining suitable potsherds for use as processing standards in such analyses is not feasible, so we suggest that bog butters represent ideal materials for such purposes. We sampled c. 450 g from two bog butter specimens and homogenised them by melting. We verified the homogeneity of both specimens by characterisation of their lipid
composition, δ 20 C values of individual lipids, and both bulk- and compound-specific radiocarbon analyses on ten sub-samples of each bog butter specimen. The weighted means of all 14 21 C measurements on the bog butter standards are 3777 ± 4 BP (IB33) and 338 ± 3 BP (IB38), thereby providing age-relevant standards for archaeological and historical fatty acids and ensuring the accuracy of radiocarbon determinations of lipids using a compound-specific approach. These new secondary standards will be subjected to an intercomparison exercise to provide robust consensusvalues.
Original languageEnglish
JournalRadiocarbon
Publication statusAccepted/In press - 11 Jan 2021

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