LIBS and LA‐ICP‐MS multielemental analysis of animal tooth M. Galiová 1 , J. Kaiser 2* , F.J. Fortes 3 , K. Novotný 1 , R. Malina 2 , T. Vaculovič 1 , L. Prokeš 1 , A. Hrdlička 1 , M. Nývltová Fišáková 4 , J. Svoboda 4 , J.J. Laserna 3 1 Department of Chemistry, Faculty of Science, Masaryk University, Kotlářská 2, 611 37 Brno, Czech Republic 2 Institute of Physical Engineering, Faculty of Mechanical Engineering, Brno University of Technology, Technická 2896/2, 616 69 Brno, Czech Republic 3 Department of Analytical Chemistry, Faculty of Sciences, University of Malaga, Campus de Teatinos s/n, 29071 Malaga, Spain 4 Institute of Archaeological Science, Královopolská 147, 612 00, Brno, Czech Republic *e‐mail: kaiser@fme.vutbr.cz Laser Induced Breakdown Spectrometry (LIBS) and Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA‐ICP‐MS) were utilized for microspatial analyses of a fossil brown bear (Ursus arctos) tooth dentin. The distribution of selected trace elements (Sr, Ba, Fe) was measured on a 26 mm x 15 mm large and 3 mm thick transversal cross section of canine tooth. The Na and Mg contest together with the distribution of matrix elements (Ca, P) was also monitored within this area. LIBS crater depths were calculated from the cross sections measured by an optical profilometer. It is shown that LIBS, similarly to LA‐ICP‐MS can be successfully utilized for fast, spatially‐resolved analysis of fossil teeth samples. In addition to microchemical analysis, the excitation temperature and the sample hardness were calculated using LIBS plasma ionic or atomic lines intensity ratios of magnesium or calcium. In order to validate the sample hardness calculations, the sample was measured with Vickers microhardness tester. The photographs of the studied sample. The investigated tooth was excavated at Dolní Věstonice II‐Western Slope, South Moravia, Czech Republic (archaeological research in 1987) and was situated closely to the famous Upper Palaeolithic triple‐burial of young people. This locality is dated to 26 640 ± 110 BP (uncalibrated 14 C data) and belongs to Gravettian. On the left image the investigated cross section of the analysed tooth (canin‐C 1 ) that belongs to brown bear (Ursus arctos) is shown (red box). Increments of cementum of teeth´s root were studied in according to determine the seasonality. This bear died at the age of 14 years in between summer and autumn season (August to October). The bars have a length of 1 cm. ACKNOWLEDGMENT M.G., J.K. and R.M. acknowledge the Ministry of Education, Youth and Sports of the Czech Republic for research project MSM 0021630508. K.N. and A.H. acknowledge the Ministry of Education, Youth and Sports of the Czech Republic for research project MSM 0021622411 and ME08002. M.N.F. and J.S. acknowledge the grant of GA AV ČR KJB800010701‐„Hunting Strategies of Upper Palaeolithic People“ and the grant of Institute of Archaeology Academy of Science of the Czech Republic No. AVOZ80010507. LA‐ICP‐MS Ablation system – UP 213 (New Wave, USA), Sample chamber – SuperCell (New Wave, USA) flushed with helium (carrier gas), ICP‐MS spectrometer – Agilent 7500 CE (Agilent, Japan). The ablation laser was used in hole drilling mode for the duration of 6 seconds for each spot. Laser ablation was performed with laser laser fluence 12 J cm ‐2 and repetition rate 10 Hz. Helium carrier gas flow of 1 l min ‐1 through the ablation cell of volume 20 cm 3 was applied. The isotopes 86 Sr, 135 Ba, 57 Fe, 23 Na, 31 P, 43 Ca and 24 Mg were measured. Additional analyses The ablation crater depth was calculated from the cross sections measured by optical profilometer MicroProf (FRT, Germany). The variation on the sample hardness nearby the LIBS ablation lines was measured by Leco LM247AT microhardness tester. Comparison of the elemental distribution obtained on the cross‐sections of fossil brown bear (Ursus arctos) canine tooth dentine utilizing LIBS and LA‐ICP‐MS. The LIBS and LA‐ICP‐MS line scans were positioned to the places shown on the photograph by red and purple color, respectively. The LIBS ablation craters had ∼200 µm in diameter and were placed in a distance of ∼500 µm from each other. The LIBS signal was averaged from 7 shots fired to the same sample position. The LA‐ICP‐MS ablation pattern consisted of ablation craters of ∼100 µm in diameter, placed in distances ∼200 µm. Na Fe Ba, Sr + ‐ LIBS Ablation laser ‐ Spectron, model SL 284, pulse width 5 ns, beam diameter 4 mm, wavelength 532 nm. Sample movement – two crossed motorized stages (PI) for both X and Y displacement. Detection system – fiber optics collector, 0.5 m focal length Czerny‐Turner imaging spectrograph (Chromex, model 500 IS, f‐number 8, fitted with interchangeable gratings of 300, 1200 and 2400 grooves mm ‐1 ) ICCD detector (Stanford Computer Optics, model 4Quik 05) with 768 x 512 pixels, each 7.8 x 7.8 µm 2 ). Spectral lines used in analysis – P (I) (253.56 nm), Mg (II) (279.55 nm, 280.27 nm), Mg (I) (285.21 nm), Fe (I) (302.40 nm), Ca (II) (315.89 nm, 317.93 nm, 370.60 nm, 373.69 nm, 393.36 nm, 396.85 nm,), Ca (I) (422.67 nm, 518.89 nm, 616.22 nm), Ba (II) (455.40 nm), Sr (I) (460.73 nm) and Na (I) (589.00 nm, 589.59 nm). Single shot analysis, laser energy (typically) ∼90 mJ/pulse. The spectra were recorded (typically) with delay and integration times 1 µs and 10 µs, respectively. Excitation temperature of LIBS microplasmas (the middle line scan across the sample) calculated assuming LTE by two‐line method [3] using Ca I (518.69 nm) and Ca I (612.22 nm) lines. [1] J.L. Tjung et al.: Elemental analysis of bead samples using laser‐induced plasma at low pressure. Spectrochim. Acta B 61 (2006) 104‐112. [2] Z.A. Abdel‐Salam et al.: Estimation of calcified tissues hardness via calcium and magnesium ionic to atomic line intensity ratio in laser induced breakdown spectroscopy. Spectrochim. Acta B 62 (2007) 1343‐1347. [3] D.A. Cremers and L.J. Radziemski, Handbook of Laser‐Induced Breakdown Spectroscopy (Wiley, Chichester, 2006). REFERENCES a) b) c) a) Estimation of the sample hardness via magnesium ionic to atomic line intensity ratios [1, 2]. In accordance with the expectations, the dentine hardness is decreasing towards the root canal. This is typical for archeological teeth samples, where part of the material near to the root canal is affected by diagenesis. b) The estimated hardness characteristic was proved by microhardness measurements. The sample was before these measurements repolished, and the test pattern was placed nearby the LIBS ablation craters for Mg detection. The distance between Vickers test dents was 100 µm. c) The ablation crater depths calculated from the cross sections measured by an optical profilometer are shown for comparison. RESULTS The results of LA‐ICP‐MS elemental mapping in two different areas (a), b)) of the sample. The (normalized) variation of the Sr/Ca, Ba/Ca, Na/Ca and Fe/Ca is plotted. The different chemical composition of the cementum (∼1 mm thick layer) can be clearly distinguished. On the frame of ongoing work we would like to exploit the LIBS capabilities for mapping, mainly by optimization of LIBS ablation crater diameter and applying double‐pulse LIBS or LIBS+LIFS techniques in order to decrease detection limits. The bar has a length of 400 μm. INSTRUMENTATION SAMPLE CONCLUSION The photograph of LIBS ablation craters created by 10 laser pulses. The bar has a length of 200 μm. a) b) Sr Ba Na Fe Laser‐ablation based analytical techniques were used for mapping and line‐ scanning of fossil animal tooth section. LIBS, similarly to LA‐ICP‐MS was proved suitable for fast, spatially‐resolved analyses of such a calcified tissues. Moreover, this technique allowed straightforward estimation of the sample hardness. From archeological point of view, on the base of these measurements it was possible to reconstruct the ethology of the fossil brown bear, i.e. the nutrition, health and migration. The measured Sr/Ca profile across the sample showed seasonal fluctuations and evidentiated the migration of this bear between his hibernaculum location and the place where the fossils were found. Together with the results from other techniques (i.e. study of cementum increments), we can conclude that this bear specimen most probably was hunted in the time when it was foraging before winter dormancy and was migrating near the human settlement. The bear was old enough and not in the best health condition, so it could be hunted. It was shown that LIBS and LA‐ICP‐MS can be successfully applied as direct or complementary techniques in spatially‐resolved microchemical analysis of fossil samples.