Effects of demineralization on the stable isotope analysis of bone samples Academic Article uri icon

Sustainable Development Goals

  • SDG 14: Life Below Water 

Abstract

  • RATIONALE: The sampling of sequential, annually formed bone growth layers for stable carbon (δ13C values) and
    nitrogen (δ15N values) isotope analysis (SIA) can provide a time series of foraging ecology data. To date, no standard
    protocol exists for the pre-SIA treatment of cortical samples taken from fresh, modern, bones.
    METHODS: Based on the SIA of historical bone, it is assumed that fresh bone samples must be pre-treated with acid prior
    to SIA. Using an elemental analyzer coupled to an isotope ratio mass spectrometer to measure stable carbon and nitrogen
    ratios, we tested the need to acidify cortical bone powder with 0.25 M HCl prior to SIA to isolate bone collagen for the
    determination of δ13C and δ15N values. We also examined the need for lipid extraction to remove potential biases related
    to δ13C analysis, based on a C:N ratio threshold of 3.5.
    RESULTS: It was found that acidification of micromilled cortical bone samples from marine turtles does not affect their
    δ15N values, and the small effect acidification has on δ13C values can be mathematically corrected for, thus eliminating
    the need for pre-SIA acidification of cortical bone. The lipid content of the cortical bone samples was low, as measured
    by their C:N ratios, indicating that lipid extracting cortical bone samples from modern marine turtles is unnecessary.
    CONCLUSIONS:We present a standard protocol for testing fresh, modern cortical bone samples prior to SIA, facilitating
    direct comparison of future studies. Based on the results obtained from marine turtle bones, pre-acidification and lipid
    removal of cortical bone are not recommended. This is especially useful as there is frequently not enough bone material
    removed via micromilling of sequential growth layers to accommodate both acid treatment and SIA. Copyright © 2015
    John Wiley & Sons, Ltd.

Publication Date

  • 2015-09-01