SpinChem™: rapid element purification from biological and geological matrices via centrifugation for MC-ICP-MS isotope analyses – a case study with Zn

Abstract

Emerging applications in isotope geochemistry using stable metal isotope systems, including those in archaeological, environmental and medical sciences, along with commercial/industrial applications such as environmental source tracing and ore exploration, require high sample throughput that conventional element purification techniques—i.e. gravity flow ion exchange chromatography (IEC)—cannot match. Here, a simple and robust method for element purification from biological and geological samples has been developed, SpinChem™, wherein element purification via IEC is greatly facilitated through centrifugation. In brief, this involves adapting chromatographic columns for encapsulation within large (50 mL) centrifuge tubes, and subsequent element purification at enhanced flow rates (1.2–1.5 mL min⁻¹) generated by centrifugal force. As proof of concept, Zn IEC purification from biological and geological materials has been detailed, demonstrating the utility of this method across the sample spectrum, and validating high yields (97 ± 4%), high separation efficiency and low contamination levels (blanks ≤1 ng). SpinChem™ IEC in the centrifuge proceeds at rates up to an order of magnitude faster than in gravity flow protocols, with 8–10 samples processed through IEC in under 2 hours (vs. 4–10 hours in gravity flow), while maintaining high subsequent MC-ICP-MS analytical precision, with average errors of 0.06‰ (2σ) or better for δ⁶⁶Zn. Benchmarking this technique using an element very sensitive to endogenous and exogenous contamination (e.g. inefficient separation and external contaminants, respectively)—Zn—exemplifies the utility and high performance of this technique, and its ready adaptation to other isotope systems of interest, including Ca, Fe, Cu, Sr/Nd, Mo and Sn.