Drug cross-contamination of latent fingermarks during routine powder dusting detected by SALDI TOF MS

Abstract

The process of dusting powders over latent fingermarks was shown to transfer drug contact residues between adjacent marks. This was seen for marks contaminated after contact with two drugs of abuse (cocaine and methadone) and three therapeutic drugs (caffeine, aspirin and paracetamol). The powders used were a commercial black powder, and α-cyano-4-hydroxycinnamic acid both of which also act as ionisation-assisting agents in laser desorption/ionisation time of flight mass spectrometry (LDI TOF MS). They were applied as the powders using a Zephyr brush, a squirrel hair brush or a magnetic wand for the magnetisable formulations of the two powders. In each case transfer of drugs from the residue-contaminated mark onto adjacent marks was detected using LDI TOF MS when the powders were applied using conventional brushes. Such transfer was not detected when magnetisable formulations were used and the powder immediately replaced with fresh magnetisable powder when a developed mark was seen.