| Objective:The injury instruments are important evidences for crimal cases at courts, and could offer some cues on the characteristics of offernders to investigators. So the discrimation of injury instruments is an one of the interesting fields for forensic pathologists. Now the method on this field is to identify by micro-morphology of wounds, but because there are so many instruments with different morphology, furthorly, the wounds with different morphology could be conducted by the same instruments on the enfluences of angle, energy, position. So the discrimation of injury instruments is not exact enough from the point of morphology. Metal injury instruments is one of the mostly used in our daily lifes, that the discrimation of it is extremely urgent. This study is to Explore the consequences of Energy Disperse X-ray Assay (EDS) and inductively coupled plasma atomic emission spectrometer (ICP-AES) in identify the metal injury instruments. Method:Two kinds of instruments were chose in this study: coated (Zn-Ni-coated spanners, Cu-coated pipes n=5) and non-coated kitchen instruments (stainless and carbon metal kitchen knives n=5). The little domestic pigs(n=12) were selected. Contusion and incisal wounds were performed on the skin by two kinds of instruments individually(n=10). Each wound was taken down completely by surgery knife and sealed in a clean box with the edge up. The cleaning skin in other places were gotten for the control (n=5). It should be important that keep the surgery knife away from touching the wounds. The samples of the second group were collected and analyzed in order to determine the discrimination capability by comparisons of concentration for trace impurities by ICP-AES. The samples were wiped with acetone and dried in the air. Subsequently, a lump of approximately 1cm2 in area was taken 5 times from the back and blade of a kitchen knife individually, After that, the taken metal was cut from the outside surface by a steel blade and used for analysis. Result: In the wounds by the coated implements,the special particles only containing Cu , Zn or Cr , Ni were found. In the wounds by non-coated kitchen implements, the particles containing Fe,Cr,Si or Fe,Mn,Si were found. Inductively coupled plasma atomic emission spectrometry (ICP-AES) is the ideal instruments with high sensitivity for the ppm level of trace elements and enough accuraty (0.001%) and precision (RSD<5%). The range (mean±2SD) of each element was compared between two samples. If the ranges overlapped of all of the elements, the samples were considered to be indistinguishable, whereas if the ranges for one or more elements were separated, the samples were considered to be distinguishable. The differences of contents of elements between the back and blade was no significant except number 5 for non-coated kitchen implements, and the significant differences of elements exited in Cr,Mn,Si,Cu,Mo among the stainless kitchen knifes, Mn, Si, among the other kitchen implements and for the blade of No. 5 knife,RSD were significant different in Mn,Si, Mo,Ti,S,P,Ni (P<0.001). Conclusion:After the examinations of wounds conducted by the two kinds of implements with SEM/EDS, the special particles with different elements are consistent with the used instruments. In addition, the quantities of elements are sigficently different between the coated and no-coated instruments. So the kinds of instruments could be discrimated by the examation of sepical particles in wounds by SEM/EDS and in the same kind, the instruments could also be discrimated by ICP-AES. SEM/EDS could examine samples quickly and not need higherrequests for samples gotten from spot, and using SEM/EDS to examine theparticles in wounds can discrimate the kinds of metal injury implements. The most low level of the samples for ICP-AES analysis could be0.001g, and we can still discrimate the different implements in the samekind by ICP-AES.
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