Automated Chronological Sequence Analysis of Intersecting Lines between Laser Printing and Seals via Pattern Selection-Based DESI-MS Imaging

Determining the chronological sequence of laser printing and seals is crucial for forensic document examination and legal evidence authentication. An automated method was developed to determine the chronological sequence between laser printing and seals via desorption electrospray ionization mass spectrometry imaging (DESI-MSI). The method employs pattern selection and an adaptive multicuster segmentation strategy, automatically adjusting segmentation parameters on the basis of similarity thresholds to handle different sample conditions. Validation on 50 samples containing intersecting laser printing and seals achieved 96% accuracy (48/50 cases) in sequence determination. An optimal similarity threshold of >0.5 was established for reliable feature selection while minimizing interference from background noise. This automated workflow eliminates manual intervention and prior knowledge requirements, providing an objective solution for forensic document authentication.