Document Type


Publication Date




Publication Title

Frontiers in Marine Science




217 (1-8)


Antioxidants are a class of molecules that provide a protective function against reactive oxygen species (ROS) in biological systems by out competing physiologically important molecules for ROS oxidation. In natural waters, the reactivity of antioxidants gives an estimate of oxidative stress, and may determine the reactivity and distribution of reactive oxidants. We present an analytical method to measure antioxidant activity in natural waters through the competition between ascorbic acid, an antioxidant, and MCLA, a chemiluminescent probe for superoxide. A numerical kinetic model of the analytical method has been developed to optimize analytical performance. Measurements of antioxidant concentrations in pure and seawater are possible with detection limits below 0.1 nM. Surface seawater samples collected at solar noon contained over 0.4 nM of antioxidants and exhibited first-order decay with a half-life of 3–7 min, consistent with a reactive species capable of scavenging photochemically produced superoxide.


© 2016 King, Berger, Helm, Irish and Mopper.

This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

Original Publication Citation

King, D. W., Berger, E., Helm, Z., Irish, E., & Mopper, K. (2016). Measurement of antioxidant activity toward superoxide in natural waters. Frontiers in Marine Science, 3, 1-8, Article 217.


0000-0001-8089-6019 (Mopper)