MICROMAPPING OF STRONTIUM TRACES IN HUMAN TEETH BY FEMTO LIBS

F. C. ALVIRA; F. RAMIREZ-ROZZI; G. A. TORCHIA; G. M. BILMES

Lima, Peru

Congreso; VIII Reunion Iberoamericana de Optica X Encuentro latinoamericano de optica, laseres y aplicacions; 2010

Pontificia Universidad Catolica del peru

Femtosecond laser-induced breakdown spectroscopy (fs-LIBS) is an atomic emission spectroscopy based on laser ablation, which improves the possibilities of spatial localization and minimal sample requirements. It is a micro-destructive technique, especially useful for unique pieces analysis. It requires no previous sample preparation and it has no limitations in sample dimensions and shapes. These abilities are highly demanded not only in material science but also in cultural heritage applications. Spatial localization is an inherent attribute of laser ablation, which combined in LIBS, with spectral analysis, gives the possibility to provide chemical information confined to restricted areas of a sample (compositional maps). In this work we show the possibilities of fs-LIBS as a nearly non destructive tool in anthropology and paleontology for the measurements of the presence and distribution of trace elements in teeth. Particularly we have built compositional micro maps of the relative strontium calcium distribution (Sr/Ca) in the enamel of three modern human teeth. On the same samples we have also analyzed the Sr/Ca ratio along the striae of Retzius. Results show a non homogeneous distribution of Sr in the enamel of the teeth, as well as constant values along the striae of Retzius, but different between them. The variation in the Sr/Ca ratios shows that any cause which has produced a change in the pattern distribution from mineral density does not reflect chronological distribution of Sr/Ca ratio These results can be useful for evolutionary anthropology studies, and particularly,  put in doubts the use of changes in Sr/Ca ratio to reconstruct age-related changes in an individual’s behaviour and/or environment.