O'Neill Kelly C, Lee Young Jin
Department of Chemistry, Iowa State University, Ames, IA, 50011.
J Forensic Sci. 2018 May;63(3):708-713. doi: 10.1111/1556-4029.13591. Epub 2017 Jul 10.
The ability to determine the age of fingerprints would be immeasurably beneficial in criminal investigations. We explore the possibility of determining the age of fingerprints by analyzing various compounds as they diffuse from the ridges to the valleys of fingerprints using matrix-assisted laser desorption/ionization mass spectrometry imaging. The diffusion of two classes of endogenous fingerprint compounds, fatty acids and triacylglycerols (TGs), was studied in fresh and aged fingerprints on four surfaces. We expected higher molecular weight TGs would diffuse slower than fatty acids and allow us to determine the age of older fingerprints. However, we found interactions between endogenous compounds and the surface have a much stronger impact on diffusion than molecular weight. For example, diffusion of TGs is faster on hydrophilic plain glass or partially hydrophilic stainless steel surfaces, than on a hydrophobic Rain-x treated surface. This result further complicates utilizing a diffusion model to age fingerprints.
确定指纹年龄的能力在刑事调查中将具有不可估量的益处。我们探索了通过基质辅助激光解吸/电离质谱成像分析各种化合物从指纹嵴向谷扩散时确定指纹年龄的可能性。研究了两类内源性指纹化合物，即脂肪酸和三酰甘油（TGs）在四种表面上新鲜指纹和陈旧指纹中的扩散情况。我们预期较高分子量的TGs扩散速度会比脂肪酸慢，从而使我们能够确定较陈旧指纹的年龄。然而，我们发现内源性化合物与表面之间的相互作用对扩散的影响比分子量的影响要强得多。例如，TGs在亲水性普通玻璃或部分亲水性不锈钢表面上的扩散速度比在疏水性雨敌处理过的表面上要快。这一结果使得利用扩散模型确定指纹年龄的情况更加复杂。
