Sorbic acid as a quantitative probe for the formation, scavenging and steady-state concentrations of the triplet-excited state of organic compounds

Sorbic acid (trans,trans-hexadienoic acid) was developed as a probe for the quantification of the formation rate, overall solution scavenging rate and steady-state concentrations of triplet-excited states of organic compounds. The method was validated against literature data for the quenching rate constant of triplet benzophenone by tyrosine obtained by laser flash photolysis and by Stern–Volmer plots of phosphorescence quenching. In contrast to these methods, the probe method does not require knowledge of the optical properties of triplets to monitor their quenching. Moreover, the probe method permits simultaneous quantification of triplet formation, quenching and steady-state concentrations during illumination of complex chromophore mixtures, such as natural organic matter (NOM), with polychromatic light >315 nm. Application of the method to de-aerated Suwannee River NOM illuminated with polychromatic light (315–430 nm) resulted in a triplet quantum yield of 0.062.

► Sorbic acid is a water-soluble probe for organic triplets.
► It was developed to quantify triplet formation, scavenging and steady-state concentrations.
► The method was validated against data from a laser flash photolysis method.
► The triplet quantum yield of a de-aerated Suwanee River NOM solution for λ = 315–430 nm was 0.062.