On the ozonation of anti-SARS-CoV-2 substances and their nucleoside analogues for mechanistic understanding of the ozone induced transformation using HPLC-ESI-Q-TOF-HRMS

-hydroxycytosine were then applied to the ozonation of molnupiravir and EIDD-1931. The investigation extended the understanding of the ozonation processes of pyrimidine-2-one derivatives and of this class of antiviral compounds through identification and elucidation of transformation products and through contribution to databases with newly reported MS/MS fragments. While 19 intermediate products and 17 more persistent products were observed, 23 transformation products were assigned identification confidence levels: 2 TPs at level 1, 7 at level 2, 17 at level 3, 4 at level 4, and 6 at level 5. The transformation mechanisms connecting the transformation products were proposed. The findings shall advance the mechanistic understanding of exposing antiviral drugs to ozonation and support the assessment of emerging pharmaceutical micropollutants.