Forensic analysis can encompass a wide variety of analytes from biological samples including DNA, blood, serum, and fingerprints to synthetic samples like drugs and explosives. In order to analyze this variety, there are various sample preparation techniques, which can be time-consuming and require multiple analytical instruments. With recent advancements in ambient ionization mass spectrometry (MS), plasma-based dielectric barrier discharge ionization (DBDI) sources have demonstrated to cover a wide range of these analytes. The flow-through design of this source also allows for easy connection to a thermal desorption type of sample introduction. We present an in-house built thermal desorption device where the sample is introduced via a glass slide, which gets heated and transferred to the DBDI-MS with nitrogen for identification and semi-quantification. Using a glass slide as an inexpensive sampling device, detection limits as low as 20 pg for fentanyl are demonstrated. Additionally, a very precise (>96% accuracy) identification of persons based on the chemical profile of their fingerprints is possible, establishing a direct analytical link of the drug trace to the individual in one measurement. We compared the DAG, TAG, sterol, and (semi-)volatile region of the averaged fingerprint spectra over multiple days, showing the best model accuracy for identification based on the DAG region. The combination of thermal desorption and DBDI-MS minimized sample preparation, leading to an ultrasensitive and rapid analysis of illicit drug traces and the identification of underlying personas based on fingerprints.
Keywords: DBDI; SICRIT; forensic; mass spectrometry; thermal desorption.
© 2023 The Authors. Drug Testing and Analysis published by John Wiley & Sons Ltd.