Formation of multimeric steroid metal adducts and implications for isomer mixture separation by traveling wave ion mobility spectrometry

Abstract

Steroid analysis is essential to the fields of medicine and forensics, but such analyses can present some complex analytical challenges. While chromatographic methods require long acquisition times and often provide incomplete separation, ion mobility spectrometry (IMS) as coupled to mass spectrometry (MS) has demonstrated significant promise for the separation of steroids, particularly in concert with metal adduction and multimerization. In this study, traveling wave ion mobility spectrometry (TWIMS) was employed to separate multimer steroid metal adducts of isomers in mixtures. The results show the ability to separate steroid isomers with a decrease in resolution compared with single component standards because of the formation of heteromultimers. Additionally, ion‐neutral collision cross sections (CCS) of the species studied were measured in the mixtures and compared with CCSs obtained in single component standards. Good agreement between these values suggests that the CCS may aid in identification of unknowns. Furthermore, a complex mixture composed of five sets of steroid isomers were analyzed, and distinct features for each steroid component were identified. This study further demonstrated the potential of TWIMS‐MS methods for the rapid and isomer‐specific study of steroids in biological samples for use either in tandem with or without chromatographic separation.

An emerging powerful technique for distinguishing isomers: Trapped ion mobility spectrometry time‐of‐flight mass spectrometry for rapid characterization of estrogen isomers

“…Cationized dimers (with higher m/z values) were characterized by higher CCS values. More importantly, better ion mobility separation of the isomers was obtained as already reported 21–23,25,26 . The difference in mobility produced by the lithiated dimers of the estradiol stereoisomers, E 2 α and E 2 β, (ΔCCS% = 10.7%, see Figure 2C) was higher than that obtained for the methoxyestradiol isomers, 2‐MeO‐E 2 β and 4‐MeO‐E 2 β (ΔCCS% = 4.3%, see Figure 2D).…”

Integrating ion mobility and imaging mass spectrometry for comprehensive analysis of biological tissues: A brief review and perspective

“…31 which is sufficient for resolving many isobaric ion species 36,66 and some isomeric ions, often with the aid of chemical derivatization 67 or metal adduction. 68,69 CCS values for many analyte classes are also frequently calculated using TWIMS-based analyses, leading to the curation of several databases for species such as proteins and steroids. 30,70 Despite being newer than some other ion mobility techniques, utilization of TWIMS already extends across many analytical disciplines.…”

Imaging Isomers on a Biological Surface: A Review

“…Even though there are still no reports about steroid imaging using IMS, the utility in the separation of steroids has been reported. [78][79][80][81][82] In 2013, Ahonen et al achieved separation of α/β-steroid isomers using TWIMS with p-toluenesulfonyl isocyanate derivatization. Derivatization was found to be e ective for an increase in the collision cross-section and/or the strength of ion/molecule interactions with the dri gas.…”

“…78) Rister et al also utilized TWIMS for underivatized structural isomers of steroid through the formation of metal adducted dimers or multimers with alkali metals. 81,82) Chouinard et al used classical DTIMS to separate underivatized stereoisomers and structural isomers of steroids as metal adducted steroid dimers. 79,80) Only Rister et al discussed the separation in mixture condition and mimetic sample as the real biological condition 81) (Fig.…”