Bersellini C, Garofano L, Giannetto M, Lusardi F, Mori G
Dipartimento di Chimica Generale, Inorganica, Analitica e Chimica Fisica, Università di Parma, Italy.
J Forensic Sci. 2001 Jul;46(4):871-7.
We propose a new process for developing latent fingerprints on metal items, applicable to unfired weapons made of Ergal in particular. The method is based on the presence of fatty acids that are contained in fingerprints and act as an insulator on the surface where fingerprints are to be developed. The process of polymerization occurs on the metal portions left untouched by finger contact. Hence, the developing process results as a negative pattern of the original fingerprint. The reaction consists in the electropolymerization of pyrrole and substituted porphyrins, i.e., tetra (o-aminophenyl) porphyrine: radical-cations are generated on superficial nucleation sites by oxidation of monomer, close to the electrode surface; subsequently, the radical species react with the neutral monomer, which begins to diffuse to the electrode. We have also studied the polymer's morphology by means of SEM and AFM, in order to find a correlation between the reagent to be used and the quality of the enhancement process. These are only preliminary results; however, they show that the suggested method is a new way to increase the rate of success in developing latent fingerprints on metal surfaces. In this regard, it may be considered complementary to other conventional procedures, due to the low costs of the instruments and reagents, and the rapidity and simplicity of the treatment.
我们提出了一种用于显影金属物品上潜在指纹的新方法，尤其适用于由6061铝合金制成的未发射武器。该方法基于指纹中所含脂肪酸的存在，这些脂肪酸在待显影指纹的表面起到绝缘体的作用。聚合过程发生在未被手指接触的金属部分上。因此，显影过程产生的是原始指纹的负像。该反应包括吡咯和取代卟啉，即四（邻氨基苯基）卟啉的电聚合：单体在靠近电极表面被氧化，在表面成核位点产生自由基阳离子；随后，自由基物种与中性单体反应，中性单体开始扩散到电极。我们还通过扫描电子显微镜（SEM）和原子力显微镜（AFM）研究了聚合物的形态，以便找出所用试剂与增强过程质量之间的相关性。这些只是初步结果；然而，它们表明所建议的方法是提高在金属表面显影潜在指纹成功率的一种新途径。在这方面，由于仪器和试剂成本低，以及处理的快速性和简便性，它可以被认为是对其他传统程序的补充。
