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).
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.
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. Trial OneTrial TwoTrial Three 6 inches straight 6 inches angled 10° 12 inches straight 12 inches angled 10°
Procedure Day 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.
Procedure Day Three Filtered the shirts. Using vacuum filtration setup we filtered the 24 samples.
Prodecure Day 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.
Procedure Day 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.
T Shirt Samples Barium Conc. (ppm) Lead Conc. (ppm) 6 in. straight Top-T11.33594.5473 6 in. straight bottom-T10.697854.1719 6 in. straight top- T21.22064.3365 6 in. straight bottom-T20.813855.4916 6 in. straight top-T31.349.3969 6 in. straight botton-T32.479226.187 6 in angle top-T10.770453.0785 6 in angle bottom-T10.57373.4544 6 in angle top-T25.66735.22 6 in angle bottom-T23.384726.039 6 in angle top-T31.12684.0228 6 in angle bottom-T32.625610.753 ICP Data 6 inch Samples
ICP Data 12 inch Samples T Shirt SamplesBarium (ppm)Lead (ppm) 12 in straight top-T10.8552114.082 12 in straight bottom-T10.49217.4843 12 in straight top-T20.646992.5193 12 in straight bottom-T20.5993.4504 12 in straight top-T30.889315.299 12 in straight bottom-T30.66788.8138 12 in angled top-T13.46396.398 12 in angled bottom-T12.699210.61 12 in angled top-T20.623785.563 12 in angled bottom-T22.35512.137 12 in angled top-T33.936511.873 12 in angled bottom-T30.504423.2191
AA Data- 6 inch Samples SampleLead (mg/mL)Barium (mg/mL) 6 in. straight Top-T118.8312.39 6 in. straight bottom-T120.8715.73 6 in. straight top- T216.2317.67 6 in. straight bottom-T222.2217.17 6 in. straight top-T343.1720.9 6 in. straight botton-T352.2220.84 6 in angle top-T120.2628.58 6 in angle bottom-T116.8428.28 6 in angle top-T248.3730.83 6 in angle bottom-T236.4229.82 6 in angle top-T320.0232.02 6 in angle bottom-T313.7430.68
AA Data-12 inch Samples SampleLead (mg/mL)Barium (mg/mL) 12 in straight top-T138.1220.9 12 in straight bottom-T135.6220.82 12 in straight top-T214.9823.79 12 in straight bottom-T215.2824.7 12 in straight top-T324.4426.2 12 in straight bottom-T344.9326.41 12 in angled top-T115.1831.86 12 in angled bottom-T113.0631.57 12 in angled top-T232.9532.38 12 in angled bottom-T216.1233.51 12 in angled top-T314.8935.53 12 in angled bottom-T39.41734.84
Conclusions The gun shot residue contained more Lead then it did Barium. We saw higher numbers from the AA because it has lower interference.
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
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