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

Abstract

Rationale Direct analysis in real time mass spectrometry (DART‐MS) provides qualitative information about additives and polymer composition. However, the observed mass spectra are dependent on sampling conditions, in particular the DART gas temperature. This report describes the combination of a heated sample stage with DART‐MS for polymer characterization. Methods Industrial polymers with different compositions were examined by thermal desorption and pyrolysis (TDPy) DART. Samples were heated on disposable copper stages from ambient temperature to 600°C, and the evolved gases were introduced directly into a DART ion source through a glass tee. Time‐ and temperature‐dependent mass spectra were acquired using a high‐resolution time‐of‐flight mass spectrometer. Kendrick mass analysis was applied to the interpretation of complex mass spectra observed for fluorinated polymers. Results Positive‐ion DART mass spectra of common polymers exhibited peak series differing by monomer masses, often accompanied by a peak corresponding to the protonated monomer. Even polymers that did not exhibit a clear series of peaks produced characteristic mass spectra. Positive‐ion and negative‐ion mass spectra were recorded for fluorinated polymers, with polytetrafluoroethylene (PTFE) producing only negative ions. Thermal desorption provided characteristic temperature profiles for volatile species such as polymer additives and polymer pyrolysis products. Conclusions In comparison with direct analysis by positioning sample directly in the heated DART gas stream, TDPy DART provides a more versatile sampling method and provides thermal separation and profiling of polymer additives, intact short polymer chains, and pyrolysis fragments.

Thermal desorption and pyrolysis direct analysis in real time mass spectrometry of Nafion membrane

“…As already mentioned above peak intensity distributions of these adducts are quite different: While (CF 2 ) n CO 2 − , (CF 2 ) n COF − and (CF 2 ) n CO 4 − are limited to n < 15, (CF 2 ) n C 2 O 4 H − series is already present at 450 C and it can be traced up to n = 35 at 503 C. This difference may be explained by relative stability of reaction products: Calculated reaction energies of (14) and (16) are −464 and − 187 kJ mol −1 , respectively. The reaction (14) is highly exothermic and (CF 2 ) n COF − may undergo further fragmentation when the number of CF 2 units is large. On the other hand, the reaction (16) is less exothermic and further fragmentation of (CF 2 ) n C 2 O 4 H − might have been suppressed.…”

“…Although the method is effective for detection of polymer additives by thermal desorption, thermal decomposition of polymers would be incomplete and it is not sufficient for polymer characterization. Recently a sample heating device was developed for thermal desorption and pyrolysis (TDP) in combination with a DART ion source and this combination was shown to be very effective to analyze polymer pyrolysis products 12–14 . This study describes the first application of the TDP/DART MS for Nafion membrane.…”

“…Recently a sample heating device was developed for thermal desorption and pyrolysis (TDP) in combination with a DART ion source and this combination was shown to be very effective to analyze polymer pyrolysis products. [12][13][14] This study describes the first application of the TDP/DART MS for Nafion membrane. A large number of pyrolysis products are identified in the mass spectra and reactions are proposed to explain their occurrence.…”

Mass propagation of Juniperus procera Hoechst. Ex Endl. From seedling and screening of bioactive compounds in shoot and callus extract

“…5-6 and Tables 5 and 6. DART-MS with the characters of rapid quantification, active compounds screening, and has offered a new research tool for herbal medicines to complete the experimental process in a very simple way [85].…”

Identifying VOCs in exhibition cases and efflorescence on museum objects exhibited at Smithsonian’s National Museum of the American Indian-New York

“…The small volume of the SPME coating makes it well-suited to interface with DART [16] by using the high-temperature gas to desorb analytes from the fiber. Although DART has been used for qualitative characterization of polymers and polymer additives [17], the application of DART-MS to investigate exhibition case materials has not previously been assessed.…”