IS OUR KNOWLEDGE ABOUT THE CHEMICAL AND PHYSICAL-PROPERTIES OF DPPH ENOUGH TO CONSIDER IT AS A PRIMARY STANDARD FOR QUANTITATIVE EPR SPECTROMETRY

The knowledge about the physico-chemical properties of the stable free radical DPPH as a primary standard for the Quantitative EPR spectrome try is summarized. It is shown how to calibrate DPPH in order to use i t as a primary EPR standard for quantitative estimations. II is expect ed that the reported data will be useful for the EPR community special ly in calibration and also for periodical checking of the standards us ed.