Colleen Justison and Shelby Bleile

Atomic Absorption

Inductively Coupled Plasma

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°

Setup

Before & After

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.

Data: Calibration Curves

T Shirt Samples Barium Conc. (ppm) Lead Conc. (ppm) 6 in. straight Top-T in. straight bottom-T in. straight top- T in. straight bottom-T in. straight top-T in. straight botton-T in angle top-T in angle bottom-T in angle top-T in angle bottom-T in angle top-T in angle bottom-T ICP Data 6 inch Samples

ICP Data 12 inch Samples T Shirt SamplesBarium (ppm)Lead (ppm) 12 in straight top-T in straight bottom-T in straight top-T in straight bottom-T in straight top-T in straight bottom-T in angled top-T in angled bottom-T in angled top-T in angled bottom-T in angled top-T in angled bottom-T

AA Data- 6 inch Samples SampleLead (mg/mL)Barium (mg/mL) 6 in. straight Top-T in. straight bottom-T in. straight top- T in. straight bottom-T in. straight top-T in. straight botton-T in angle top-T in angle bottom-T in angle top-T in angle bottom-T in angle top-T in angle bottom-T

AA Data-12 inch Samples SampleLead (mg/mL)Barium (mg/mL) 12 in straight top-T in straight bottom-T in straight top-T in straight bottom-T in straight top-T in straight bottom-T in angled top-T in angled bottom-T in angled top-T in angled bottom-T in angled top-T in angled bottom-T

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