Figure 3.

Diphenylanthracene (DPA) trapping of ¹O₂ as diphenylanthracene endoperoxide (DPAO₂) in a CCl₄ layer after the decomposition of ONOO⁻ in an aqueous layer in a biphasic system (see Methods). These reactions were carried out with and without the ¹O₂ trap TME in the CCl₄ layer. Perylene was present in the CCl₄ layers at constant concentrations in all of the experiments, and served as an internal standard. (A) Stepwise decomposition of ONOO⁻ in the aqueous layer in the absence of TME in the CCl₄ layer (solution A; see Methods); the HPLC elution profile exhibits three fractions, each representing unreacted DPA, perylene, and DPAO₂, respectively. B shows the result of an analogous decomposition experiment as in A, but with 78 mM TME in the CCl₄ layer (solution B; see Methods). C is the elution profile of a positive control in which ¹O₂ was generated from the highly efficient H₂O₂/OCl⁻ reaction in the aqueous layer (solution A). D shows the result obtained after an experiment analogous to the one in C, except that the CCl₄ solution contained 78 mM TME (solution B). The results shown in C can be used to estimate the amount of ¹O₂ generated in the decomposition of ONOO⁻, shown in A.