The first is EDTA, the reagent regularly used in ancient DNA extraction.
EDTA is carbon-rich and synthesized from sources that contain only stable carbon isotopes (“old” carbon, .
(c) Overview of the sample preparation workflows used for radiocarbon dating and genetic analysis.
We also detect no skews in radiocarbon dates compared to untreated samples.
Given the different material demands for radiocarbon dating (500 mg of bone/dentine) and DNA analysis (10–100 mg), combined DNA and collagen extraction not only streamlines the sampling process but also drastically increases the amount of DNA that can be recovered from limited sample material.
Since carbon contamination may also arise from organic molecules that have entered the bone or tooth matrix through soil detritus, microbial invasion or post-excavation handling, ABA-gelatinization is often followed by ultrafiltration through membranes that separate high molecular weight collagen chains from shorter peptides, amino acids and other small molecules.
DNA extraction, in contrast, is typically performed by lysis of the bone/tooth matrix using extraction buffers containing ethylenediaminetetraacetic acid (EDTA), a chelating agent that dissolves hydroxyapatite by means of sequestering calcium ions, and proteinase K, an enzyme that digests collagen and other proteins.