(by Chloe Cao, Chemistry Team)
This past week the chemistry group has been working with ivory samples (elephant tusk, mammoth tusk, and elk teeth). We used Raman spectroscopy, Inductively-Coupled Plasma - Mass Spectroscopy (ICP-MS), and Matrix Assisted Laser Desorption/Ionization- Time Of Flight (MALDI-TOF) mass spectroscopy.
Using Raman spectroscopy, we observed that it was easier to get a better spectrum with ivory than with bone. We also found that it was hard to compare the ratio of peak heights due to the fact that ivory was not photobleached by the laser for an extended amount of time. The literature had mentioned that their samples were bleached for about 12 hours. We had bleached ours for a maximum of 3 hours.
ICP-MS was also conducted using the ivory samples. We tested for the same elements that we tested with the non-ivory samples and hoped to see if comparative analysis can identify which elements were more dominant in each sample. The data from this procedure is still being analyzed, but as of now, it appears that there are many of overlaps in counts per second due to a large standard error.
For MALDI, we went to Johns Hopkins University. Dr. Phil Mortimer was very helpful with set-up and insight to calibration. While we were running the samples at Hopkins, we were able to obtain good peaks and a variety of spectra. We did have trouble with some of the samples since the peaks were too high, which prevented from seeing all the peaks that we needed to see. Another problem we faced was with the mammoth tusk sample since there were barely any peaks in the spectra. After consulting with Terry Weisser, we think it might be because the tusk was fossilized. We are hoping to run some new samples at Hopkins this next Tuesday to see if we can get better spectra. One thing that we hope will improve the spectra is to increase the sample size, especially for the mammoth tusk. It is possible that the reason why our spectra did not let us see all the peaks that we needed to see was because the laser was too strong. Furthermore, we might not have had a lot of digestion because the ivory was electrostatic and stayed predominantly on the walls of the Eppendorf vial.