Identification of Common Cutting Agents in Latent Fingerprints by High-Performance Liquid Chromatography–Electrospray Ionization–Quadrupole Time-of-Flight Mass Spectrometry (HPLC-ESI-qToF-MS)

Abstract

Fingerprint analysis is widely used in forensic science, primarily for individualization. However, fingerprints are rich with other information pertaining to an individual’s activities; several studies have used matrix-assisted laser desorption/ionization-time of flight (MALDI-ToF) to determine these factors but have been hampered by issues such as the choice of matrix and the time-consuming preparation of samples. Consequently, most analyses are performed using high performance liquid chromatography (HPLC) triple quadrupole instruments which offer high levels of sensitivity and fragment information. These instruments are, however, low resolution which means the mass spectral data can only be expressed to 2 decimal places and require further supporting information such as retention time to ascertain the compounds in the fingerprint. This is especially true if the compounds in question are isobaric. We report a rapid and accurate method of identifying individuals that have been in contact with commonly found cutting agents via latent fingerprint analysis using liquid chromatography electrospray quadrupole time-of-flight mass spectrometry (LC-ESI-qToF-MS). This is the first publication to utilize LC-ESI-qToF-MS instrumentation in both positive and negative modes, obtaining exact mass data used to identify and confirm the presence of cutting agents in latent fingerprints. High resolution mass spectral data have been obtained, which can be reported to 4 decimal places and compared to the theoretical exact mass data of each individual component to within a 5 part per million (ppm) error limit.