Imaging of methamphetamine incorporated into hair by MALDI-TOF mass spectrometry

Matrix-assisted laser desorption ionization (MALDI)–time-of-flight (TOF) mass spectrometry (MS) was used for visual demonstration of methamphetamine (MA) incorporation into human hair. Longitudinal sections of human scalp hair shafts from chronic MA users were directly subjected to imaging MS. Numerous MA-positive spots with various intensities were observed in the specimens, which probably reflect habitual MA abuse and the different MA blood levels upon each administration. This imaging MS method for drugs in hair seems to give much more accurate chronological information on drug use, and clearer discrimination between deliberate drug use and passive exposure, using only a single hair shaft. This is the first report of imaging MS applied to forensic toxicology. This method is expected open a new field in analyses of drugs in hair.