Gas-Phase Dynamics of Collision Induced Unfolding, Collision Induced Dissociation, and Electron Transfer Dissociation-Activated Polymer Ions

Abstract

Polymer characterizations are often performed using mass spectrometry (MS). Aside from MS and different tandem MS (MS/MS) techniques, ion mobility-mass spectrometry (IM-MS) has been recently added to the inventory of characterization technique. However, only few studies have focused on the reproducibility and robustness of polymer IM-MS analyses. Here, we perform collisional and electron-mediated activation of polymer ions before measuring IM drift times, collision cross-sections (CCS), or reduced ion mobilities (K 0 ). The resulting IM behavior of different activated product ions is then compared to non-activated native intact polymer ions. First, we analyzed collision induced unfolding (CIU) of precursor ions to test the robustness of polymer ion shapes. Then, we focused on fragmentation product ions to test for shape retentions from the precursor ions: cation ejection species (CES) and product ions with m/z and charge state values identical to native intact polymer ions. The CES species are formed using both collision induced dissociation (CID) and electron transfer dissociation (ETD, formally ETnoD) experiments. Only small drift time, CCS, or K 0 deviations between the activated/formed ions are observed compared to the native intact polymer ions. The polymer ion shapes seem to depend solely on their mass and charge state. The experiments were performed on three synthetic homopolymers: poly(ethoxy phosphate) (PEtP), poly(2-n-propyl-2-oxazoline) (Pn-PrOx), and poly(ethylene oxide) (PEO). These results confirm the robustness of polymer ion CCSs for IM calibration, especially singly charged polymer ions. The results are also discussed in the context of polymer analyses, CCS predictions, and probing ion-drift gas interaction potentials.

Ion mobility spectrometry – Mass spectrometry coupling for synthetic polymers

“…Most importantly, sodium adducts of poly(ethylene oxide) (PEO) exhibit robust gas‐phase structure with respect to instrumental conditions, consistent with earlier DTIMS studies that have demonstrated that the spherical shape of small PEO/Na + complexes is temperature‐independent ( vide infra ) . Similar findings regarding the conformational robustness of sodiated PEO were recently reported by Haler et al while investigating the gas‐phase dynamics of ion unfolding upon different activation methods . Moreover, Duez et al also showed a linear correlation between the CCS values derived from DTIMS experiments performed in helium and those obtained in TWIMS when using nitrogen as the drift gas .…”

High-Throughput Multi-attribute Analysis of Antibody-Drug Conjugates Enabled by Trapped Ion Mobility Spectrometry and Top-Down Mass Spectrometry

“…The Δ3 voltage, which was applied in the TIMS funnel 1, is useful for desolvation and declustering of ions entering the TIMS device, but may fragment or dissociate a cysteine-linked ADC if the voltage is too high. 48 This is similar to the impact that the TIMS DC gradient has on TIMS separation performance. While the Δ3 voltage and TIMS cell collision energy largely affect desolvation, the Δ6 voltage is applied at the end of the TIMS accumulation tunnel and affects the trapping and release efficiency of ions into the TIMS tunnel for separation (Figure S1).…”

“…The parameters found to have the greatest impact on the TIMS separation performance were the Δ3 voltage, the Δ6 voltage, the TIMS RF, and the TIMS cell collision energy (Table S1 and Figure S1). The Δ3 voltage, which was applied in the TIMS funnel 1, is useful for desolvation and declustering of ions entering the TIMS device, but may fragment or dissociate a cysteine-linked ADC if the voltage is too high . This is similar to the impact that the TIMS DC gradient has on TIMS separation performance.…”

Fundamental Studies on Poly(2-oxazoline) Side Chain Isomers Using Tandem Mass Spectrometry and Ion Mobility-Mass Spectrometry

“…Such differences can be seen in the cation ejection species. The cation ejection species are constituted of the intact precursor ions not yet having undergone any fragmentation, but having ejected one or several sodium cations (sum of all the species; see Figure 4) [41]. Figure 4 monitors the relative intensities of the precursor ions (SY curves in Figure 2 In a Pn/i-PrOx mixture, the two polymer contributions can hence also be titrated using the cation ejection species.…”