Two analytical approaches quantifying the electron donating capacities of dissolved organic matter to monitor its oxidation during chlorination and ozonation

Electron-donating activated aromatic moieties, including phenols, in dissolved organic matter (DOM) partially control its reactivity with the chemical oxidants ozone and chlorine. This comparative study introduces two sensitive analytical systems to directly and selectively quantify the electron-donating capacity (EDC) of DOM, which corresponds to the number of electrons transferred from activated aromatic moieties, including phenols, to the added chemical oxidant 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonate) radical cation (i.e., ABTS•+). The first system separates DOM by size exclusion chromatography (SEC) followed by a post-column reaction with ABTS•+ and a spectrophotometric quantification of the reduction of ABTS•+ by DOM. The second system employs flow-injection analysis (FIA) coupled to electrochemical detection to quantify ABTS•+ reduction by DOM. Both systems have very low limits of quantification, allowing determination of EDC values of dilute DOM samples with