Electron spin resonance (aka Electron Paramagnetic Resonance) is the gold standard for spin-trapping of NOx and ROx species in biomedical research. Our easy-to-use, low-cost Benchtop instrumentation renders this technique accessible to scientists and researchers at all levels. There is no longer any need to wait for shared facilities. TEMPOL in water or buffer can be measured at concentrations as low as 0.5 micro-molar. Hyperfine splitting is also readily observable. Micro-ESR is the ultimate cost-effective solution for routine ESR spin trapping studies.