Less is more: Limiting semi-invasive sampling for multi-isotope analyses and increasing data output from single aliquot samples

Developments in multi-isotope applications now enable the production of direct and precise life history data of studied archeological and paleoanthropological specimens, with analysis of tooth enamel proving particularly powerful in deep-time preservation contexts. However, the increasing amount of sample material necessary too-often compromises the specimen's structural integrity. Finding ways of minimizing semi-invasive sampling while maximizing produced data thus becomes increasingly crucial. In this study, we examine ways of optimizing sample use for state-of-the-art isotope measurements of enamel-bound zinc (δ⁶⁶Zn), an increasingly used method in multi-isotope archeological research. We show that certain desolvating nebulizer introduction systems can be used to measure δ⁶⁶Zn with high efficiency and accuracy using less than half the usual sample size. Moreover, we demonstrate that remaining samples subjected to typical pretreatments used for tooth enamel carbonate (δ¹³C and δ¹⁸O) studies can be safely used without alterations to δ⁶⁶Zn values. Similarly, we highlight that the often-discarded matrix fraction from zinc chromatography can be utilized for further analyses, such as measurements of ⁸⁷Sr/⁸⁶Sr ratios. Our results underscore the possibility of extracting the maximum information from specimens while altogether avoiding or significantly reducing semi-invasive sampling.