We report a dual probe system that can be used to assess the relative production of photochemically generated one-electron oxidants in aqueous systems containing dissolved organic matter (DOM). Conversion of 4’-substituted biphenyl-2-carboxylic acids to the corresponding benzocoumarins by triplet excited states of chromophoric dissolved organic matter (3CDOM*) is highly sensitive to the electronic nature of the substituent. In contrast, benzocoumarin formation via hydroxylation of the aromatic ring by hydroxyl radical is less sensitive to substituent effects. Differences in the relative production of the two benzocoumarins can be used to estimate the contributions of 3CDOM* and hydroxyl radical to biphenyl-2-carboxylic acid oxidation. Application of the probe pair to natural water samples and organic matter isolates reveal marked differences in the photochemical production of 3CDOM* and hydroxyl radical.

Biphenyl carboxylic acid probe pair for quantifying photochemically generated hydroxyl radical and excited triplet states in aqueous systems containing dissolved organic matter

253rd National Meeting (2017)

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