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Spin Labels

Most chemical and biological samples of interest for ESR spectroscopy lack an inherent stable unpaired electron, the majority of ESR methods rely on the usage of spin-labeling reagents. Commonly, nitroxides such as derivates of TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy) are used as they offer high stability of the unpaired electron and exceptional ESR sensitivity combined with facile and versatile moieties for binding to the sample through chemical reactions. Sigma-Aldrich offers a comprehensive array of spin labels suitable for ESR spectroscopy in high purities to allow for easy interpretation of the analytical results.

Product #


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382000 4-Carboxy-TEMPO, free radical 97%
253596 16-DOXYL-stearic acid, free radical
176141 4-Hydroxy-TEMPO 97%
371343 4-Hydroxy-TEMPO benzoate, free radical 97%
253367 4-(2-Iodoacetamido)-TEMPO free radical
76381 4-Isothiocyanato-TEMPO for ESR-spectroscopy, ≥97.0%
179485 4-Oxo-TEMPO