Description Packaging 1 g in glass bottle Application Spin-label that has been used to study molecular migration and long-term stability of seeds and pollen. Has been covalently attached to oligonucleotides to prepare a DNA probe sensitive to electron spin resonance. The acetoxymethyl ester is an esterase-sensitive probe that crosses the blood-brain barrier for electron spin resonance-computed tomographic imaging. Spin-label. The anionic form has been used to determine distribution coefficients of neutral solubilizates in anionic micelles. Used in the preparation of a tetraphenylporphyrin bearing a nitroxyl radical.