In situ analysis of free radicals from the photodecomposition of hydrogen peroxide using a frequency-mixing magnetic detector.

We present an analytical method for the real-time detection of free radicals from the photodecomposition (ultraviolet radiation, λ = 254 nm) of hydrogen peroxide (H2O2) using frequency-mixing magnetic detection. We monitored the free radicals in situ without catalysts or probe molecules. Both water and H2O2 produced frequency-mixing signals under UV radiation, but the water signal was much weaker. The root mean square amplitude of the frequency-mixing signal was found to depend on the initial H2O2 concentration. Considering the physical properties of the reactants, the frequency-mixing signal is attributed to the generation of paramagnetic free radicals by the photodecomposition of H2O2. [ABSTRACT FROM AUTHOR]