Microfluidic sample preparation of mammoth tooth enamel for amino acid dating Laila Patinglag 1 , Marc Dickinson 2 , Kirsty E.H. Penkman 2 and Kirsty J. Shaw 1* 1 Faculty of Science and Engineering, Manchester Metropolitan University, UK 2 Department of Chemistry, University of York, UK Fossil records date back from hundreds to millions of years ago and through dating methods, these preserved remains of life can be arranged chronologically. This is crucial in reconstructing evolutionary history and understanding responses to environmental changes that can aid with modern conservation efforts and addressing climate change 1 . Radiocarbon dating is limited to ~50,000 years but amino acid racemization allows direct dating of calcium carbonate-based biominerals (e.g. bone and teeth) over quaternary timescales (~2.5 million years) 2 . Amino acid dating measures the D/L ratio of intra-crystalline amino acids trapped within fossil samples and therefore protected from the external chemical environment for the duration of diagenesis. However, current amino acid dating methodology relies on specialist laboratory equipment, relatively large sample sizes and lengthy processing times 3 . By exploiting the advantages of miniaturization, microfluidic systems are an attractive alternative to these current methods. Here, we demonstrate a microfluidic approach for sample preparation to isolate the intra-crystalline amino acids from mammoth tooth enamel. Using a microfluidic device, sample size was reduced from ~30 mg to 1 mg, which gives an opportunity to analyse a wider range of fossils, particularly as a less destructive method for precious samples. Isolation of the intra-crystalline amino acids was carried out by oxidation, with comparable results achieved in 2 hours compared to the traditional method of 72 hours. Results showed a marked improvement to the corresponding macroscale conventional method in terms of sample size and oxidative treatment time. Miniaturization did not significantly affect the yield and composition of the extracted intracrystalline amino acids, especially the four key amino acids (Asx, Glx, Ala and Phe). This microfluidic methodology has the potential to enable sample treatment on site and operate a less destructive sampling procedure for precious fossil samples. References 1. Fordham et al., Using paleo-archives to safeguard biodiversity under climate change, Science, 369, 6507 (2020). 2. Demarchi, Amino acid racemization dating, Encyclopedia of Earth Sciences Series, 13-26, (2015).Dickinson et al., A new method for enamel amino acid racemization dating: A closed system approach, Quaternary Geochronology, 50, 29-46 (2019).
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