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EPR in a nutshell

Unique and Far-reaching

EPR (Electron Paramagnetic Resonance) spectroscopy is the only technique that unambiguously detects and quantifies species with unpaired electrons. These species include free radicals, transition metals and defects in materials.

EPR spectroscopy is featured in many disciplines such as medical science, biology, chemistry, physics, material science, archeology and forensics. This wide spread use is a direct result of the crucial role of free radicals and transition metals in many processes such as photosynthesis, oxidation/reduction, catalysis, and polymerization reactions .

Free radicals may also play a damaging role to their surroundings. Free radicals are involved in cancer, aging, Alzheimer’s, and cardiovascular diseases. Degradation of material properties such as brittleness and discoloration of polymers is frequently a result of free radical reactions.

Versatile and Nondestructive

In EPR spectroscopy, the sample can be a solid, a liquid, a gas, colored solutions, turbid solutions, or even a cell suspension. In the EPR measurement there is no contact with the sample so the sample is preserved for other analyses.

Easy to use

EPR is a very accessible spectroscopy. Sample preparation is minimal, just requiring placing the sample in a tube regardless whether the sample is a solid, liquid, or gas. Detection of unpaired electrons in both free radicals and in transition metals is unambiguous. From the EPR spectrum it is easy to obtain precise quantitative information about the radicals present. Also the EPR spectrum can be fitted to improve the quantitative results and to precisely extract parameters to characterize the species and compare with literature.


Each laboratory has its own requirements for preparing and measuring their samples. In some cases the sample may require special sample holders to position the sample in the EPR spectrometer. Other cases may require irradiation with UV light or heating and cooling of the sample to generate the radicals or to observe changes in the sample due to the exposure. The specialized equipment necessary for these cases is available for each laboratories needs.

A step by step look inside EPR

Inside EPR