Thermal degradation of β-carotene studied by ion mobility atmospheric solid analysis probe mass spectrometry: full product pattern and selective ionization enhancement

Atmospheric solid analysis probe mass spectrometry has the capability of capturing full product patterns simultaneously including both volatile and semi-volatile compounds produced at elevated temperatures. Real-time low-energy collision-induced fragmentation combined with ion mobility separations enables rapid identification of the chemical structures of products. We present here for the first time the recognition of full product patterns resulting from the thermal degradation of β-carotene at temperatures up to 600 °C. Solvent vapor-induced ionization enhancement is observed, which reveals parallel thermal dissociation processes that lead to even- and odd-numbered mass products. The drift-time distributions of high mass products, along with β-carotene, were monitored with temperature, showing multiple conformations that are associated with the presence of two β-rings. Products of masses 346/347, however, show a single conformation distribution, which indicates the separation of two β-rings resulting from the direct bond scission at the polyene hydrocarbon chain. The thermal degradation pathways are evaluated and discussed.