Carbon-Based Fingerprint Powder as a One-Step Development and Matrix Application for High-Resolution Mass Spectrometry Imaging of Latent Fingerprints

Carbon-based materials are often used as matrices for matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) and its imaging (MALDI-MSI). However, researchers have refrained from using carbon-based fingerprint powder (CFP) as a matrix due to high background and contamination. In this work, the compatibility of CFP is reevaluated with MALDI-MSI using a high-resolution mass spectrometer (HRMS) and compared to traditional organic matrices. Relevant fingerprint compounds were easily distinguished from carbon cluster peaks when using HRMS. For fair comparison, half of a fingerprint was dusted with CFP while the other half was dusted with traditional organic matrices. All compounds studied had comparable, or higher, signal-to-noise (S/N) ratios when CFP was used as the matrix. Additionally, chemical image qualities closely followed the trend of S/N ratios. CFP proved to be an effective one-step development and matrix application technique for MALDI-MSI of latent fingerprints, when carbon cluster peaks are well separated by a HRMS.