A simplified, non-automated, DGA-based resin protocol for the separation of Ca, Sr and REE: Validation for Ca, stable and radiogenic Sr isotopic compositions

The combined analysis of calcium, stable and radiogenic strontium isotopic compositions ( δ 44 Ca/ 42 Ca, δ 88 Sr/ 86 Sr and 87 Sr/ 86 Sr, respectively) and rare earth elements (REE) provides information for the reconstruction of diet, mobility, and associated diagenetic status of the studied tissue in bioarchaeological studies. However, their combined application is often limited by complex multi-step chromatographic procedures, reliance on automated systems, large sample requirements, and high analytical costs. Here, we present a simplified, non-automated one-step chromatographic protocol based on DGA resin that enables the sequential separation of Sr, Ca and REE from a single sample aliquot for further isotope analyses. The method was validated using six certified reference materials representing organic and inorganic matrices relevant to biological, geological, and environmental materials applicable to bioarchaeological studies. Chromatographic elution profiles demonstrate efficient and reproducible separation of matrix elements, Sr, Ca and REE, with quantitative elemental recoveries and minimal cross-contamination. The resulting δ 44 Ca/ 42 Ca, δ 88 Sr/ 86 Sr and 87 Sr/ 86 Sr values are in excellent agreement with published reference data, confirming the accuracy of the protocol. This procedure requires no automated equipment, uses a reusable resin, a limited number of acids, and compared to multi-step chromatographic techniques, reduces chemical handling and processing time. By maximizing the analytical information obtained from limited material, this affordable and accessible protocol facilitates integrated isotopic investigations of diet, mobility, and preservation in bioarchaeology, and is readily applicable to other fields of study in Earth and environmental sciences.