Investigation of the free radical stability of 2,2-diphenyl-1-picrylhydrazyl upon storage in hydrogen- and electron–donning solvents at different temperatures

Samples containing free radicals are stored at various temperatures which has large impact on the radical stability. The current work shows that lower storage temperatures enhance the stability of 2,2-diphenyl-1-picrylhydrazyl radical by preserving peak shapes. The g-factor exhibited higher stability with time as the temperature decreased. Electron-donating solvents, such as tetrahydrofuran, showed improved stability, with the analyte free radical concentration decreasing only 24 % and 8 % at refrigeration and freezing conditions, respectively, compared to 99 % at room temperatures. Hydrogen-donating solvents showed limited improvement at reduced temperatures, with tetralin displaying a 99 % decrease of spin concentration at both low temperature storage conditions.