Experimental Study Of Gunshot Residue Spot Test On Impact Marks By Portable X-Ray Fluorescence Spectrometry

The detection of impact marks plays an important role in inferring the types of guns,reconstructing the trajectory and analyzing the plot of shooting cases.At present,the examiners test the impact marks mainly using the morphological characteristics.For some impact marks which have poor quality of morphological characteristics,it is necessary to test the gunshot residue.Color test is a commonly method for spot test of gunshot residue,which is destructive and can only be used for qualitative detection of single element.However instruments of the forensic laboratory such as scanning electron microscopy and energy dispersive spectrometer have poor portability and long detection period.In this paper,portable X-ray fluorescence spectrometer was used to test the gunshot residue on the impact marks made by Chinese Norinco QSZ-92 9mm pistol on textiles,wood,steel plate,iron sheet,ceramic tile and concrete objects.The portable X-ray fluorescence spectrometer has a good effect on testing the elements of Sn,Sb,Pb,Cu,Zn on impact marks on textile objects under the test time of 90 s with the plastic mode(select the main range wave plate).In the samples,on one hand the contents' ratio of Cu and Zn has certain stability,on the other hand the Sn and Sb elements can be tested at the same time in the shooting distance of 25cm(including 25cm),after the shooting distance of 50cm(including 50cm),the Sn and Sb elements can not be tested at the same time.The portable X-ray fluorescence spectrometer can be widely applied to the detection of impact marks on wood,steel plate,ceramic tile and concrete objects.The elements of Cu,Zn and Pb can be find in the result which tested by the portable X-ray fluorescence spectrometer.It is not recommended to use portable X-ray fluorescence spectrometer to test the impact marks on iron sheet objects.In this paper,a method of rapid detection of impact marks by portable X-ray fluorescence spectrometer was established,which can make reference to spot test of impact marks in shooting cases.