Characterization of Fluorinated Polymers by Atmospheric-Solid-Analysis-Probe High-Resolution Mass Spectrometry (ASAP/HRMS) Combined with Kendrick-Mass-Defect Analysis

Abstract

Fluorinated polymers are a diverse and important class of polymers with unique applications. However, characterization of fluorinated polymers by conventional mass spectrometric methods is challenging because (i) their high fluorine contents make them insoluble or only sparingly soluble in most common solvents and (ii) commonly used matrices employed for MALDI do not desorb or ionize them efficiently. In this work, atmospheric-solid-analysis-probe (ASAP) high-resolution orbitrap mass spectrometry (HRMS) was used as a new tool for the molecular characterization of various fluorinated polymers, including polyvinylidene fluoride (PVDF) and fluorinated copolymers containing PVDF and chlorotrifluoroethylene (KEL-F 800) or PVDF and hexafluoropropylene (Viton A and Tecnoflon). The major peaks of the observed distributions were assigned compositions, but the high number of species required the use of an alternative method to treat such complex data. Kendrick-mass defects (KMD) were calculated on the basis of the "common-to-all" vinylidene difluoride repeating unit. By plotting the KMD as a function of the nominal Kendrick masses (NKM), specific patterns based on homologous series emerged. Kendrick maps were therefore drawn to simplify the mass spectra and provide confident peak assignments through homologous-series recognition. A specific fingerprint for each polymer has been identified, and the ability to discern the four species present in a blend through KMD analysis was demonstrated.

Thermal desorption and pyrolysis direct analysis in real time mass spectrometry for qualitative characterization of polymers and polymer additives

“…It is exemplified with the TDPy‐DART analysis of a polyvinylidene fluoride (PVDF) sample (Figure ). A low TIC is recorded below 450°C, but a rich mass spectrum displaying polymeric ion series with a repeating unit at 64.01 Da corresponding to C 2 H 2 F 2 can still be extracted, highlighting the sensitivity of the DART‐MS configuration to capture the tiniest piece of information. Peaks are assigned to (CH 3 , H)‐PVDF adducted with O 2 * − /NO 2 − /(H)CO 3 − most probably being pristine low‐molecular‐weight PVDF chains released upon thermal desorption.…”

New mass spectrometry concepts for characterization of synthetic polymers and additives

“…This can be largely attributed to the effective deconvolution of polymeric complexity using post-ionization separation of characteristics such as architectural differences. [19][20][21][22][23][24] Improvements and decreasing prices of (ultra)high-resolution mass analyzers enabled by Orbitrap technologies have also driven the field, but less so for polymer MS. [25][26][27] Integral to advances in MS are developments in ionization technology that could provide improvements in simple and direct characterization abilities. Atmospheric pressure and subsequently 'ambient' approaches to ionization have been implemented and a few have shown applicability to synthetic polymer characterization.…”

Uncovering Xenobiotics in the Dark Metabolome using Ion Mobility Spectrometry, Mass Defect Analysis and Machine Learning

“…20,21 Furthermore, since PFAS have varying head groups and linkages including hydrocarbon regions (fluorotelomer sulfonate (FTSs)), ether bonds (PFECAs) and branched C-F backbones, 10,12 subclass distinction is possible even within this single xenobiotic class. [29][30][31][32][33][34][35] Orthogonal separation dimensions have also shown utility for PFAS analyses. In a study coupling liquid chromatography, ion mobility spectrometry and MS (LC-IMS-MS), the multidimensional evaluations uncovered specific PFAS trends as the m/z versus IMS collision cross section (CCS) plots distinguished each PFAS subclass studied.…”