T02_07

Achieving low backgrounds during compound-specific hydroxyproline dating: HPLC column effects

Linscott B¹,  Spindler L¹, Chivall D¹, Zelechonok Y², Wood R¹

¹University of Oxford, Oxford, United Kingdom, ²SIELC Technologies , Wheeling, United States of America

AMS radiocarbon dating is central to the development of robust chronologies in archaeological and paleoenvironmental contexts spanning the last 50,000 years. For dates to be accurate, samples must be free of exogenous carbon contamination. At the Oxford Radiocarbon Accelerator Unit (ORAU), considerable advancements in the dating of bone collagen have been made through the development of a high performance liquid chromatography (HPLC) method for the dating of the amino acid hydroxyproline (HYP), which can mitigate the effects of exogenous carbon contamination (1). However, recent changes in ligand manufacturing methods for the reverse-phase mixed-mode HPLC column (Primesep A, SIELC Technologies; IL, USA) used in the ORAU HYP protocol have resulted in unacceptably high analytical backgrounds. Prior to the manufacturing change, backgrounds (measured on background-age hydroxyproline isolated from Pleistocene bison bones) of 50k BP were achievable. Since the manufacturing change, due to column bleed, a mean background of 32.8k BP using hydroxyproline isolated from the same bones has been measured. The Primesep A column is no longer suitable for compound-specific amino acid radiocarbon measurements of older material. Here, we present background data and the chromatography conditions used to isolate hydroxyproline using an alternative column from the same manufacturer,  which shows promising potential as an alternative for the routine isolation and AMS dating of hydroxyproline - especially approaching the limits of the method. 

1. Deviese, T., Comeskey, D., McCullagh, J., Bronk Ramsey, C. and Higham, T., 2018. New protocol for compound‐specific radiocarbon analysis of archaeological bones. Rapid Communications in Mass Spectrometry, 32(5), pp.373-379.