Chemical Composition of Latent Fingerprints by Gas Chromatography–Mass Spectrometry. An Experiment for an Instrumental Analysis Course

With recent advances in modern technology, forensic scientists have begun to examine whether more information than just ridge patterns might be obtained from fingerprints left at a crime scene. Analysis of the chemical composition of fingerprints could allow a suspect pool to be reduced even if the prints obtained from the scene were smudged or patterns were not matched in a database. This forensic-based experiment is designed for upper-division chemistry majors taking an instrumental analysis course. Students collect their own latent fingerprints and then extract various chemical components from the residue including fatty acids and cholesterol. Using a common silylating agent, the constituents are derivatized for analysis by gas chromatography (GC) with quadrupole mass spectrometric (MS) detection. From chromatographic retention times and MS data, students can identify the components present in their fingerprint residue and compare their results, demonstrating the existence of compositional differences and the presence of certain chemical markers which have the potential to be used for individualization.