A nuclear magnetic resonance (NMR) method for detecting hydrogen peroxide includes stimulating a spin signal in a liquid sample in a static magnetic field by exciting the sample with a first electromagnetic pulse having a frequency corresponding to a hydrogen NMR frequency; after a first time period, refocusing the spin signal by a series of second electromagnetic pulses also having the NMR-corresponding frequency and separated by a first echo time, while sampling a first train of spin signals; and refocusing the spin signal by a series of third electromagnetic pulses having the NMR-corresponding frequency and separated by a second echo time while sampling a second train of spin signals, the second echo time different from the first echo time. First and second spin-spin relaxation times are derived from the trains of spin signals, and a quotient of the spin-spin relaxation times indicates the presence of hydrogen peroxide.