Abstract
ABSTRACTThe analysis of processing standards alongside samples for quality assurance in radiocarbon (14C) 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 butter represents an ideal material for such purposes. We sampled ca. 450 g from two bog butter specimens and homogenized them by melting. We verified the homogeneity of both specimens by characterization of their lipid composition, δ13C values of individual lipids, and both bulk- and compound-specific radiocarbon analyses on 10 sub-samples of each bog butter specimen. The weighted means of all 14C 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 consensus values.
Highlights
Identifying and obtaining suitable natural materials for use as radiocarbon (14C) standards to provide quality assurance for radiocarbon measurements is of primary importance (Bryant et al 2000; Scott et al 2004)
The pretreatment procedure initially involves the simultaneous extraction of fatty acids (FAs) from the clay matrix and their methylation into fatty acid methyl esters (FAMEs) using a methanolic/sulphuric acid
We present (i) the selection process used to identify two bog butter finds to be prepared as radiocarbon processing standards, (ii) their cleaning, (iii) their homogenization, and (iv) their homogeneity assessment by lipid composition, stable carbon isotope and radiocarbon analyses
Summary
Identifying and obtaining suitable natural materials for use as radiocarbon (14C) standards to provide quality assurance for radiocarbon measurements is of primary importance (Bryant et al 2000; Scott et al 2004). Inter-laboratory comparisons on standard materials are important to aid radiocarbon laboratories in detecting possible biases (offsets) in their 14C measurements (Rozanski et al 1992; Bryant et al 2000; Scott et al 2004). At the University of Bristol, we recently developed a new method for radiocarbon dating potsherds from their absorbed lipid residues (Casanova et al 2017, 2018, 2020a). This method uses a compound-specific radiocarbon analysis (CSRA) approach based on commonly recovered food residues: C16:0 and C18:0 fatty acids (FAs), characteristic of degraded animal fats (Casanova et al 2018). The pretreatment procedure initially involves the simultaneous extraction of FAs (and other lipids) from the clay matrix and their methylation into fatty acid methyl esters (FAMEs) using a methanolic/sulphuric acid
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
