Optimising sample preparation for strontium isotopic analysis: A new study by Eco Research
Sample preparation in the laboratory is a crucial step preceding instrumental analysis and can significantly influence the quality of the final results. In research, analytical methods are continuously refined to ensure the highest data quality, but this often involves time-consuming procedures and a high consumption of materials, such as the single-use application of resin in solid-phase chromatographic separations.
A recent study conducted by Eco Research and published in Talanta Open explored a potential solution to make these processes more efficient. The investigation focused on optimising the chromatographic separation on selective resin, a fundamental step for isolating strontium prior to isotopic analysis.
The results show that replicated samples or samples from the same batch (e.g. from the same sampling site) can be processed on the same resin cartridge, provided that the resin is thoroughly cleaned and regenerated between samples. This approach allows for a reduction in time and material use without compromising data quality, especially when samples exhibit low isotopic variability – information that can be derived from previous knowledge of the sampling site or from geo-lithological data. In cases where such information is lacking or when working with unique, non-replicable samples, it is advisable to maintain the traditional approach to ensure maximum analytical reliability.
Overall, this study provides a concrete contribution to the optimisation of laboratory methodologies, promoting a more sustainable use of resources and greater efficiency in research activities.
A B S T R A C T
One of the key passages to achieve an accurate and precise Sr isotope ratio (87Sr/86Sr) measurement is the Sr/matrix separation. Traditionally this step is accomplished using a Sr-spec resin which allows the Sr recovery eliminating the main interferent species (namely Ca, Rb, Pb). While this application is consolidated, few details are available in literature regarding the possibility to reuse the resin for the consecutive separation of Sr from multiple samples. To deepen this aspect, in this study different tests were conducted both using certified and in-house reference materials, to check the performance of the separation in different working conditions and testing solutions of HNO3 and HCl for the resin washing between consecutive use cycles. These tests confirmed that resin reuse guarantees average Sr recovery higher than 95 %, with a negligible presence of interfering species in the final solution, and no effect on the Sr isotope ratios. However, since in no case a quantitative Sr recovery was achieved, the presence of Sr residues on the resin might limit this application if different samples are treated on the same resin. Tests with batches of real samples showed that using a mild washing with HNO3 (0.05 M), although residual cross-contamination was present, no significant alteration of the sample 87Sr/86Sr ratios occurred, in case of homogeneous ratios. At increasing levels of heterogeneity, even the use of HCl in the resin washing might be not sufficient. This study demonstrated the feasibility of resin reuse, reducing its consumption, associated costs, and lab workload, without affecting the accuracy of the results when working with sample replicates or when a low-to-medium difference in the 87Sr/86Sr ratio of consecutive samples is expected.