An optical hydroxyl radical sensor.

A hydroxyl radical (.OH) fibre-optic sensor has been developed. An .OH radical-sensitive reagent phase (nitrophenol) was immobilized onto XAD-7 methacrylate beads. Subsequently the beads were attached to the distal end of a polymethylmethacrylate fibre optic. Nitrocatechol, generated from the attack of .OH radical on nitrophenol, exhibits a strong absorption band in the visible region of the electromagnetic spectrum (lambda max = 510 nm). Here, reflectance spectroscopy was employed to monitor the concomitant intensity decrease in the reflectance spectrum upon .OH radical attack. The sensor exhibited excellent stability and linearity of response to .OH generated by a Fenton reaction system (EDTA, Fe(II) and H2O2) with H2O2 over the concentration range of 3.6 x 10(-6)-8.0 x 10(-2) M.