Antimony can carry information that concentration alone cannot provide. Its stable isotope composition can help compare sources, follow environmental transfers and test the provenance of materials in mining, environmental, archaeological and industrial systems.
Antimony is considered a critical and strategic metal, its use is omnipresent in industry: paints, batteries, munitions, brake pads, flame retardants... Its isotopes therefore provide information on both industrial and environmental traceability.
Antimony is a metal rarely found in isolation. It is most often found in areas with high mineralization, particularly where sulfur concentrations are significant. It also frequently occurs alongside arsenic, another toxic metalloid. Therefore, it is not uncommon to find antimony in mining or industrial settings, even when the mining operation does not directly extract the antimony.
Because of its omnipresence in our industrial applications, antimony can end up in the environment in many ways: via mining and metallurgical industries, road dust, incineration ash, military training grounds... Because of its mobility (especially in its reduced form), it is found in water, soil and sediments.
These isotopic ratios can therefore inform us both about the origin of the material and about the processes that occurred during its transport. For example, in an environmental study, understanding the processes that remobilize antimony contaminants is essential for directly addressing its transfer vectors and reducing the risks and costs associated with remediation.
The analytical challenge is not only to measure Sb, but to isolate very small amounts of it from complex matrices without modifying its isotope composition. The workflow combines selective purification with hydride-generation multi-collector ICP-MS.
Solid samples are digested and water samples are conditioned so that Sb can be isolated from the surrounding matrix.
Antimony is selectively retained using thiol-functionalized mesoporous silica powder (TSP), allowing major matrix elements and potential interferents to be removed.
Purified Sb is converted into volatile hydrides, strongly increasing transport efficiency and sensitivity for low-concentration samples.
The ¹²³Sb/¹²¹Sb ratio is measured by hydride-generation multi-collector ICP-MS and expressed as δ¹²³Sb relative to an isotope reference solution.
Only a small total amount of Sb is required for the purification and isotope measurement workflow.
Low blank levels make the method suitable for samples containing relatively small quantities of Sb.
Efficient removal of elements including As, Cd, Co, Cr, Cu, Fe, Ni, Pb, Se and Sn.
High recovery after purification, with no detectable isotope fractionation introduced by the procedure.
Sb quantification limit: 0.008 ± 0.001 µg/L using HG-ICP-MS.
External reproducibility for δ¹²³Sb, reported as 2 standard deviations.
Purified Sb isotope solutions were measured by HG-MC-ICP-MS at approximately 1 µg/L Sb.
The method was validated across CRMs ranging from 0.026 µg/mL Sb in blood to 850 µg/g in fly ash.
Analytical values are based on Ferrari et al. (2021), validated on 14 environmental, geological, biological and anthropogenic certified reference materials. The exact preparation route is adapted to the matrix and available Sb mass. View the publication →
The value of Sb isotopes lies in comparison. A sample becomes informative when its isotope composition is compared with potential sources, reference materials, spatial trends or process-related changes.
If potential sources have different δ¹²³Sb signatures, isotope measurements can help determine whether Sb in a soil, water or sediment is compatible with mining, metallurgical, traffic-related or other anthropogenic inputs.
Spatial variations in Sb isotope composition can help identify which tributary, source area or material contributes to the Sb load measured downstream.
Sb isotope signatures can be compared between raw materials, ores and manufactured products to investigate whether they are compatible with the same geological or industrial origin.
Sb isotope ratios may also change during transport and reaction. When combined with concentration, mineralogy and water chemistry, this can provide information on how Sb is mobilised, retained or transformed.
The strongest interpretation combines δ¹²³Sb with Sb concentration, geochemistry, candidate source signatures and knowledge of the processes acting on the system.
All Rights Reserved by IsotopiX