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Analyzing Gun Shot Residue using the ICP and AA

Colleen Justison and Shelby Bleile. Analyzing Gun Shot Residue using the ICP and AA. Atomic Absorption . Inductively Coupled Plasma . Gun Shot Residue . Gun powder burns quickly to produce rapid expansion of gas

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Analyzing Gun Shot Residue using the ICP and AA

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  1. Colleen Justison and Shelby Bleile Analyzing Gun Shot Residue using the ICP and AA

  2. Atomic Absorption

  3. Inductively Coupled Plasma

  4. Gun Shot Residue • Gun powder burns quickly to produce rapid expansion of gas • The three major elements are lead (Pb), barium (Ba), or antimony (Sb).

  5. Purpose • The purpose of our experiment was to observe the residue left on a person that had been shot at two different distances and angles. • We used the AA and ICP to analyze the shirts and determine the amount of Barium and Lead found on them.

  6. Procedure Day One • Cut t-shirts into “10x10” pieces. • Shot a 9 mm • Cut the shirts in half to give a total of 24 samples.

  7. Setup

  8. Before & After

  9. ProcedureDay Two • We made a 0.3 M solution of nitric acid from a 16 M solution. • Used to soak the t-shirts to remove the solid from the shirts and put it into solution. • Made standards of Lead and Barium. 1, 5, 10, 15, 20, 25 ppm. • Let the shirts soak in the acid for 24 hours.

  10. Procedure Day Three • Filtered the shirts. Using vacuum filtration setup we filtered the 24 samples.

  11. ProdecureDay four • Ran our standards and samples using the AA. • found that we needed to make higher concentrated standards because we had residue at higher ppm. • The new standards we made were 10, 20, 40, 60, and 80 ppm of Lead and Barium.

  12. ProcedureDay Four Cont. • We ran all 24 samples on both the ICP and AA. • We found that the ppm was greater on the AA then on the ICP.

  13. Data: Calibration Curves

  14. Data: Calibration Curves

  15. ICP Calibration • Barium Coefficient: 0.9886 • Equation: y=623897x+1313.6 • Lead Coefficient: 0.9998 • Equation: y=1342.66x+24.6818

  16. ICP Data 6 inch Samples

  17. ICP Data 12 inch Samples

  18. AA Data- 6 inch Samples

  19. AA Data-12 inch Samples

  20. Comparisons

  21. Comparisons – Contd.

  22. Comparisons – Contd.

  23. Comparisons – Contd.

  24. Comparisons – Contd.

  25. Comparisons – Contd.

  26. Conclusions • In general, the gun shot residue contained more Lead then it did Barium. • We saw higher numbers from the AA because it has lower interference. • The top of the angled shirts showed more metals than the bottom half. • The bottom of the straight shirts showed more metals than the bottom half. • The distances did not differ as much as expected.

  27. Future Work • Use different guns/bullets and test for metals • Test for Antimony as well as Lead and Barium • Shoot from more angles and distances • Use the XRF to observe the samples

  28. Acknowledgements Thank you to Chris for making our lives a lot easier during this project and for Andrew for putting up with us all semester. Thank you to the Chemistry department for funding our experiment

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