Hydroxyl and 1-Hydroxyethyl Radical Detection by Spin Trapping and GC-MS

The detection of free radicals is often carried out by electron spin resonance (ESR) techniques. The procedure is specific and very sensitive (provided the radicals have a sufficiently long half-life to be measured). In the case of extremely short-lived free radicals, which are difficult to directly detect by ESR, spin-trapping procedures have been developed based on reaction of highly reactive radicals with a “spin trap,” generating an adduct free radical having a longer half-life and suitable for detection by regular ESR procedures (
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4
). A variety of spin traps have been described in the literature, each optimal for given experimental conditions or specific free radicals to be detected (
1
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4
). Hydroxyl (OH) radical detection by spin trapping and ESR procedures often has been done using 5,5-dimethylpyrroline N-oxide (DMPO) as the spin trap (
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). This spin trap very rapidly reacts with OH to produce a stable free radical adduct having a characteristic ESR spectrum (
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).