Sampling and Pretreatment of Tooth Enamel Carbonate for Stable Carbon and Oxygen Isotope Analysis

Abstract

Stable carbon and oxygen isotope analysis of human and animal tooth enamel carbonate has been applied in paleodietary, paleoecological, and paleoenvironmental research from recent historical periods back to over 10 million years ago. Bulk approaches provide a representative sample for the period of enamel mineralization, while sequential samples within a tooth can track dietary and environmental changes during this period. While these methodologies have been widely applied and described in archaeology, ecology, and paleontology, there have been no explicit guidelines to aid in the selection of necessary lab equipment and to thoroughly describe detailed laboratory sampling and protocols. In this article, we document textually and visually, the entire process from sampling through pretreatment and diagenetic screening to make the methodology more widely available to researchers considering its application in a variety of laboratory settings.

Ecological flexibility and adaptation to past climate change in the Middle Nile Valley: A multiproxy investigation of dietary shifts between the Neolithic and Kerma periods at Kadruka 1 and Kadruka 21

“…Following diagenetic assessment by FTIR-ATR, enamel powder samples were pre-treated following established protocols [ 172 ]. Samples were purified using 0.2–0.4 ml (dependent on individual sample weight) of dilute 0.1 M acetic acid for 10 min, followed by three rinses with ultrapure water to neutralise the samples [ 172 , 173 ].…”

The use of stable isotopes in postconflict forensic identification

“…As enamel contains very little collagen (i.e., ≤1%, Lee‐Thorp, 2002), the bleaching step can be of shorter duration using more dilute NaOCl/H 2 O 2 than used during bone bioapatite extraction (e.g., Chesson et al, 2019; Kusaka & Nakano, 2014). Some researchers suggest skipping this treatment altogether as any organics present in the sample should not react with the phosphoric acid used during analysis to produce CO 2 (Ventresca Miller et al, 2018). In this case, a weak (ca.…”

“…0.1 M) acetic acid solution would be the only pretreatment required to prepare tooth enamel for stable isotope ratio analysis. Again, this treatment is of shorter duration (i.e., ≤30 min) than that used when preparing bone bioapatite (e.g., Chesson et al, 2019; Kusaka & Nakano, 2014; Ventresca Miller et al, 2018).…”

New Chronology for Megalithic Burials in Vidarbha (Central India): Insights Into Contemporary Hydro-Climate and Food Habits

“…Although bone collagen would be preferred for radiocarbon ( 14 C) dating (Bronk Ramsey et al 2004;Brock et al 2013;Calabrisotto et al 2013;Higham et al 2015;Cersoy et al 2017), in circumstances of poor bone preservation, the carbonate fraction of bio-apatite derived from tooth enamel is a suitable alternative material for radiocarbon dating (Saliège et al 1995). Bio-apatite derived dates should be cross-validated by other suitable means to minimize the confounding effect of secondary carbonates in tooth enamel (Hedges et al 1995;Grün 2006;Buchholz and Spalding 2010;Zazzo 2014;Ventresca 2018;Dury et al 2021). As a cross-validation of bio-apatite dating, we also undertook 14 C dating of organic food residue material derived from cooking pots among burials.…”

“…Many studies have inferred that skeletons of mammalian herbivores contained the isotopic signature(s) of vegetation and habitat (δ 13 C and δ 18 O values) in which they have lived (Cerling et al 2004;Kohn et al 2005;Ventresca et al 2018;Morandi et al 2021;Sandhu et al 2021). Thus hydroxyapatite from animal bone and tooth enamel are appropriate for isotopic analyses when skeletal remains are poorly preserved, and they retain a secure stable isotopic record for thousands of years (Schoeninger and DeNiro 1982;Thorp and van der Merwe 1987;Wang and Cerling 1994).…”