Measurement of gaseous hydrogen peroxide with a liquid core waveguide chemiluminescence detector

Hydrogen peroxide is an important atmospheric oxidant that is photochemically produced. It is typically present in the atmosphere at low to sub-part per billion by volume (ppbv) levels. Typically, enzyme-mediated fluorogenic techniques are used for the sensitive measurement of H2O2. We present here a simple luminol chemiluminescence (CL) measurement of H2O2 with a liquid core waveguide (LCW)based instrument. The LCW acts both as a reaction cell and a light collector and terminates in a conventional, high numerical aperture optical fiber that carries the CL emission to an inexpensive photomultiplier tube (PMT). Gaseous hydrogen peroxide is collected with a high efficiency Nafion membrane diffusion scrubber. The H2O2 in the scrubber effluent is quantified by Co(II)-catalyzed oxidation of alkaline luminol. The linear range is at least up to 100 ppbv H2O2. A limit of detection (LOD) of 25 pptv H2O2 is achieved with an inexpensive miniature photomultiplier tube (PMT). The interference equivalent ozone is ~<0.5%. At typical ambient levels, NO2 and SO2 do not interfere.