Spin trapping

Spin trapping is an analytical technique employed in chemistry and biology for the detection and identification of short-lived free radicals through the use of electron paramagnetic resonance (EPR) spectroscopy. EPR spectroscopy detects paramagnetism species such as the unpaired electrons of free radicals. However, when the half-life of radicals is too short to detect with EPR, compounds known as spin traps are used to react covalently with the radical products and form more stable adduct that will also have paramagnetic resonance spectra detectable by EPR spectroscopy. The use of radical-addition reactions to detect short-lived radicals was first proposed by E. G. Janzen in 1965.