A Polysorbate Structural Atlas Curated from Drift Tube Ion Mobility-Mass Spectrometry Measurements

Polysorbates (PSs) are mixtures of synthetic surfactants with widespread use in different application areas. PSs are particularly important in pharmaceutical and biotherapeutic formulations owing to their ability to minimize aggregation and surface adsorption. However, PSs are known to undergo degradation and autoxidation which can alter their efficacy. While studies have been conducted to better understand the chemical composition of PSs, comprehensive chemical characterization is challenging due to the heterogeneity of commercial PSs which contain numerous molecules representing both active surfactants and byproducts of synthesis. These complex mixtures result in extensive isomer and isobar species confounding characterization. Here, we utilize structurally selective drift tube ion mobility-mass spectrometry (DTIMS-MS) to compile a collision cross section (CCS) structural atlas for commonly found species in both polysorbate 20 and 80 (PS-20 and PS-80), two of the most commonly used PSs. This comprehensive IM-MS survey discovered a total of 536 molecules with discrete chemical formulas (350 in PS-20 and 186 species in PS-80), with each CCS measurement exhibiting high analytical reproducibility (<0.4% RSD, n ≥ 4 replicates). The primary chemical species found from electrospray spectra of US Pharmacopeia standards were singly charged monoesters and nonesterified species, with larger PS molecules favoring higher charge states. This first-of-a-kind, highly curated CCS database for PSs resulted in 41 empirically defined mobility-mass correlations (PS structure vs mass) that predict the location of individual PS oligomer species from IM-MS data for improved characterization.