ICP‐MS/MS for Strontium Isotope Studies: Potential for Archaeological Provenance Studies

Inductively coupled plasma‐tandem mass spectrometry (ICP‐MS/MS) enables nearly interference‐free determination of trace elements in different matrices. Furthermore, its mass resolution, combined with mass‐ and reaction‐filtering, allows the measurement of several isotope systems that are otherwise difficult to analyse due to significant interferences. The 87 Sr/ 86 Sr ratio has been widely used in geochronology and geochemistry, increasingly also in archaeology as a provenance proxy. Because of limited Sr‐isotope variations in archaeological materials, high‐precision thermal ionisation mass spectrometry (TIMS) or multi‐collector inductively coupled plasma mass spectrometry (MC‐ICP‐MS) techniques have been preferred. In this study, we conducted a comparative analysis of the 87 Sr/ 86 Sr ratio from 14 faunal and human tooth enamel samples using TIMS and ICP‐MS/MS with SF 6 reaction gas. Our results show that the relative difference in the 87 Sr/ 86 Sr ratio between these methods is less than 0.001 (i.e., < 0.1%), which is sufficient for provenance studies in the geologically complex areas with larger variability in bioavailable strontium isotopic composition. The precision of the ICP‐MS/MS technique limits its suitability for establishing the bioavailable strontium Sr‐isotope ratio baselines, but it can be a fast and cost‐effective method in (1) distinguishing values that significantly deviate from the local bioavailable 87 Sr/ 86 Sr ratio, (2) filtering those samples that differ remarkably from the average of a larger sample and (3) assessing the homogeneity of the archaeological data.