Oxidation of the cyanobacterial hepatotoxin microcystin-LR by chlorine dioxide: Reaction kinetics, characterization, and toxicity of reaction products

Tomas P.J. Kull*, Peter H. Backlund, Krister M. Karlsson, Jussi A.O. Meriluoto

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

82 Citations (Scopus)

Abstract

Cyanobacteria are known producers of cytotoxins, hepatotoxins, and neurotoxins. The main toxins are microcystins, cyclic heptapeptide hepatotoxins, produced by strains of several cyanobacterial genera frequently found in eutrophied freshwaters. Due to the acute and chronic toxicity of microcystins, successful removal of these toxins in drinking water treatment processes is of increasing concern. In the present work the kinetics of microcystin-LR (MC-LR) oxidation by chlorine dioxide (ClO2) was studied with UV-spectrometry and high performance liquid chromatography (HPLC). Characterization of reaction products was performed with mass spectrometric (MS) analysis, while the toxicity of reaction products was tested with a protein phosphatase inhibition assay (PPIA). The main reaction products formed, dihydroxy isomers of MC-LR as identified by MS, were nontoxic according to the PPIA. The overall rate constant k for the reaction between MC-LR and ClO2 at 293 K and pH 5.65 was modest, k = 1.24 M-1 s-1, suggesting that ClO2 is not a suitable oxidant for the degradation of microcystins in drinking water treatment processes.

Original languageEnglish
Pages (from-to)6025-6031
Number of pages7
JournalEnvironmental Science and Technology
Volume38
Issue number22
DOIs
Publication statusPublished - 8 Nov 2004
MoE publication typeA1 Journal article-refereed

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