Structural analysis of synthetic opioids using travelling wave ion mobility-mass spectrometry (TWIM-MS).

Traveling wave ion mobility-mass spectrometry (TWIM-MS) has emerged as a powerful tool for the identification of synthetic opioids, such as fentanyl and its analogs. However, due to its novelty, only a few fentanyl analogs have been studied using this technology and alternative drift gases, apart from the commonly employed nitrogen gas. Here we introduce the largest compendium of measured TWCCSN2, TWCCSHe, and TWCCSCO2 values for fentanyl-related compounds. This compendium of mobility-derived CCS molecular descriptors for precursor [M + H]+ ions can be used to assign fentanyl identities. Here, we report collision-cross section (CCS) values for precursor [M + H]+ ions of 110 fentanyl analogs, 7 fentanyl precursors, and 31 non-fentanyl related synthetic opioids measured using three mobility gases; nitrogen, helium, and carbon dioxide. Measured TWCCSN2 values show high agreement with previously published collision cross-section values obtained via drift-tube ion mobility (DTIM) MS, with differences ranging from -0.1 to 1.3%. Additionally, computationally derived CCS values for each fentanyl analyte were calculated using MobCross, with a difference range of ±3-15% between theoretical and experimental values.