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 ^TWCCS_N2, ^TWCCS_He, and ^TWCCS_CO2 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 ^TWCCS_N2 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.