Rapid Characterization of Polymer Materials Using Arc Plasma-Based Dissociation-Mass Spectrometry

Abstract

Fingerprinting spectra of polymer materials containing information of monomers' molecular weight and detailed structure, constituents, and sequences were obtained by a direct analytical process using arc plasma-based dissociation (APD)−mass spectrometry. The thermal arc plasma generated using a simple arc discharge device induces the dissociation of the polymeric backbone, producing mass spectra with strong regularity within seconds. The molecular weight of the repeating unit was revealed by equal intervals between peak series and protonated monomer ions in the mass spectra. Meanwhile, lots of secondary fragment ions were produced to provide abundant structural information. For polyethers, it is even possible to decipher (read) the "sequence" directly from their spectra. Polymers composed of isomers or only differing in their initiator moieties were easily distinguished with their characteristic APD mass spectra. The spectra were highly reproducible according to the results of similarity calculation. Unlike pyrolysis mass spectrometry, in the APD device, polymers in liquid, solid, powder, and crude samples can be analyzed directly without any pretreatment, and the regular spectra are easier to interpret. Compared with other direct analytical methods, more structural informative spectra can be acquired owing to the high energy, high temperature, and unique chemical reactivity of arc plasma. Thus, this technique is promising to be a valuable tool in rapid elucidation of polymer materials.

Three-Dimensional Mass Spectral Imaging of Polymers Via Laser-Assisted Micro-Pyrolysis Program with Flowing Atmospheric-Pressure Afterglow Ambient Mass Spectrometry

“…The series with a slightly positive slope showing the m / z difference of 68.0626 is assigned to fragments of polyisoprene (C 5 H 8 ) n , which is the adhesive material of duct tape. The series with a more positive slope showing the m / z difference of 44.0262, which corresponds to (C 2 H 4 O) n , may be assigned to PEG surfactants . Also, peaks with a mass difference corresponding to C 13 H 11 O 2 are also detected, which are assigned as PET fragments.…”

“…As the laser duty cycle increases from 20 to 100%, the pyrolysis products of PE with a series of (CH 2 ) n become evident and more fragments at higher m / z appear. Besides the pyrolysis products of PE that show a horizontal line in the KMD plot, another line with a positive slope is also present with the m / z difference corresponding to (C 2 H 4 O) n , which is likely from the polyethylene glycol (PEG) ethers that are used as surfactants. , …”

“…Besides the pyrolysis products of PE that show a horizontal line in the KMD plot, another line with a positive slope is also present with the m/z difference corresponding to (C 2 H 4 O) n , which is likely from the polyethylene glycol (PEG) ethers that are used as surfactants. 22,24 In the case of PET (Figures S4 and S5), additives can be identified in FAPA-only mode and at a lower laser duty cycle. For example, in the positive ion mode, protonated diethylhexyl phthalate (DEHP, C 24 H 39 O 4 + ), which is a plasticizer, 22 ).…”

“…The series with a more positive slope showing the m/z difference of 44.0262, which corresponds to (C 2 H 4 O) n , may be assigned to PEG surfactants. 24 Also, peaks with a mass difference corresponding to C 13 H 11 O 2 are also detected, which are assigned as PET fragments. However, the intensity of the PET fragments is much lower than that of the PI fragments, which is likely due to the high desorption efficiency of the PI adhesive component.…”

Rapid Chemical Screening of Microplastics and Nanoplastics by Thermal Desorption and Pyrolysis Mass Spectrometry with Unsupervised Fuzzy Clustering

“…Here, no GC separation is conducted, drastically reducing the analysis time with a trade-off of more complicated spectra. In addition, high-resolution mass analyzers and soft ionization provide more intact molecules and more accurate elemental compositions relative to the EI–quadrupole MS. Ambient ionization techniques such as direct analysis in real time (DART) − and arc plasma-based dissociation have demonstrated chemical analysis of polymers, with more recent works on DART , and atmospheric solid analysis probe , moving into microplastic analysis.…”