Utilization of fingerprint dusting powder in tracking fingerprint aging using MALDI-TOF-MS

Abstract

Tracking of fingerprint aging will provide valuable forensic value for crime investigation as trust in traditional fingerprint evidence has been declining over the years and a practical standard procedure has not been established. Chemical analysis of fingerprints by matrix-assisted laser desorption/ionization mass spectrometry has been utilized in previous research and has been shown to be capable in tracking fingerprint aging. However, the usage of conventional matrices in current protocol is undesirable as they disrupt the integrity of fingerprint samples. Hence, this project aims to validate the usage of fingerprint-dusting powders in substitution of conventional matrices in the forensic study of fingerprint aging by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS).

This study will focus on a fingerprint dusting powder known as Silver/Black a commercial product manufactured by Sirchie. Silver/Black was characterised and their performance by MALDI-TOF-MS in fingerprint aging was studied. Silver/Black was selected due to the presence of stearic acid in it that could function as a proton donor that may enhance ionization efficiency. Silver/Black was found to be able to detect biomarkers from fingerprints at a satisfactory quality in ambient/accelerated aging over 28 days. Sunlight simulation was also conducted that stimulated sunlight exposure of 28 and 92 days respectively. Silver/Black was able to produce satisfactory results in ambient aging with peak m/z 297.5 showing consistent decreasing trend when compared from Fresh to Day 28 with statistical significance. Silver/Black also produced promising results in sunlight simulation aging with peak m/z 341.5 showing statistical significance and a consistent increasing trend. Therefore, Silver/Black can be utilized as a matrix in future experiments in the tracking of fingerprint aging using MALDI-TOF-MS.

Future work will focus on the optimization of fingerprint dusting powders, verification of current findings by utilising more robust techniques and optimizing experiment conditions as well as sample preparation