Hydroxyl radical probe for analysis in natural waters.

R. Plummer, C. Dube, D.W. King

[Equation Omitted] Hydroxyl radicals are one of the most important oxidizing agents present in natural waters. Due to its low, steady state concentration, OH cannot be measured directly. However, several probes such as methanol and phenol have been used to measure OH flux. We have used p-hydroxyphenylacetic acid (pOHPAA) as a OH probe. We have found that the reaction of OH with pOHPAA in the presence of Cl- produces a directly measurable fluorescent dimer. We hypothesize that the mechanism involves intermediate radicals formed by the reaction of OH with chloride providing site-specific oxidation of pOHPAA followed by dimer formation.