A new tool to human provenancing? Neodymium in a forensic and archaeological context. Esther Plomp (e.plomp@vu.nl), Isabella von Holstein, Laura Font, Janne Koornneef, Jason Laﬀoon and Gareth Davies Deep Earth Cluster, Faculty of Earth and Life Science (FALW), Vrije Universiteit Amsterdam, The Netherlands 1. Introduction Isotope analyses have increas- ingly been used over the last decade to decipher human diet and migration in forensic [1,2] and archaeo- logical investigations [3,4]. Commonly used isotopic systems (Sr-Pb, O-H) for human prov- enancing studies, however, have limitations. Thus the inclusion of another isotope system is necessary to provide further validation of the technique and to improve the spatial resolution. Neodymium isotopes (143Nd/144Nd) are a potential tool that may compliment currently utilised systems. In this pilot study a latest generation thermal ionization mass spectrometer (TIMS, TRITON- Plus), at the Vrije Universiteit, Amsterdam (Fig. 1), was used to measure sub- nanogram amounts of Nd in modern human teeth to demonstrate the applicability of the Nd isotope technique to human provenancing. Enamel and dentine from third molars belonging to 35 modern Dutch inhabitants were sampled. Due to low concentrations of Nd in human teeth all the enamel and dentine was sampled and prepared using various methods (Fig. 2) acquiring sample sizes of generally ~0.5g, up to ~1g. These sample quantities are enormous compared to what is required for Sr analysis (1-3 mg), complicating sampling and chemical processing. Sampling bulk enamel and dentine was found to be most eﬃcient using a hand-held drill. The teeth were dissolved and processed using chromatographic procedures, and were analysed using TIMS. Due to the low Nd concentrations the samples were analysed using 1013 Ohm ampliﬁers. The internal precision and external reproducibility has been demon- strated to be better for small samples in comparison to the standard 1011 Ohm ampliﬁers [10]. 4. Nd Results Nd concentrations in human teeth were found to be very low, generally vary- ing from 0.3 to 3 ppb, with some exceptions of concentrations up to 30 ppb (Fig 3.). The 143Nd/144Nd isotope ratios in individual teeth usually fall within or above the currently deﬁned Dutch local range, which is based on Dutch river sediment data [11, 12], fossil animal bones [7] and archaeological glass [3] (Fig. 3). As all individuals analysed lived within the Netherlands, it was expect- ed that their Nd values would fall within the local range. This is the case for the majority (n=10) of the individuals. Some individuals (n=2) show slightly elevat- ed neodymium ratios. It is possible that these individuals fall outside of the currently deﬁned local range as the data used to construct this range is not di- rectly comparable to modern human individuals. It was possible for 3 out of 12 individuals to measure the sample with both 1013 and 1011 Ohm ampliﬁers (Fig 4). In these cases the 143Nd/144Nd ratios of both measurements are within error (2 SD), validating the 1013 Ohm ampliﬁer measurements on human tissues. 5. Conclusion Preliminary results show that low Nd concentrations in modern human teeth are within analytical capabilities, however, the analytical pro- cess is still challenging. The 143Nd/144Nd isotope results in tooth enamel of Dutch individuals illustrate the potential of Nd isotopes as an additional provenance tool that may provide a more complete image of the geo- graphical origins of individuals. Ongoing work to reﬁne the method is being completed before it is applied to modern human remains in forensic investigations and archaeological remains. 143Nd is expressed relative to the stable, non-radiogenic isotope 144Nd: the 143Nd/144Nd isotope ratio (comparable to the 87Sr/86Sr ratio). Geological variations of 143Nd/144Nd generally range from 0.510 in the oldest parts of the earth to 0.514 in recent mantle derived lavas [5]. Nd has limited mobility during weathering process