Simple, Fast, and Ultrasensitive Fluorescent Detection of Peroxymonosulfate in Chemical, Enzymatic, and Cellular Systems

Abstract

Peroxymonosulfate (PMS) is widely used in advanced oxidation processes (AOP) to remove organic contaminants from wastewater. A simple method for determining PMS is necessary to dose this oxidant effectively and use it adequately in AOP. Here, we report a simple, fast, and accurate method for quantifying PMS using a pro-fluorescent boronate redox probe. In contrast to previously described methods, the proposed assay does not require activation of PMS by a low-valent transition metal. Based on the determined second-order rate constant of the direct oxidation reaction of the coumarin-7-boronic acid probe with PMS (2k = 1.1 × 104 M–1 s–1), we have developed a method based on high-performance liquid chromatography coupled with fluorescence detection (HPLC-FLD) for ultrasensitive detection of PMS with a detection limit of 5 nM and a quantification limit of 40 nM. The HPLC-FLD method enables detection of PMS in real water samples, confirming its practical usefulness. The reported method enables the determination of PMS over a wide pH range and in the presence of common ions. It also enables tracking of PMS formation in sulfite solutions. Using activated RAW 264.7 macrophages, we demonstrate the feasibility of real-time monitoring of PMS production using a plate reader with fluorescence detection, along with appropriate control experiments.