Department of Civil & Environmental Engineering, University of Cincinnati, 765 Baldwin Hall, Cincinnati, Ohio 45221-0071, USA.
Environ Sci Technol. 2010 Oct 1;44(19):7238-44. doi: 10.1021/es1000243.
Degradation of the cyanotoxin microcystin-LR (m/z 995.5) using sulfate radical-based advanced oxidation technologies (AOTs) and identification of reaction intermediates formed during treatment were investigated in this study. To the best of our knowledge this is the first study on the degradation and identification of reaction intermediates for any cyanotoxin with SO(4)(•-). Tandem mass spectrometry designated the formation of nine (as m/z) reaction intermediates with four of them (m/z 1011.5, 1027.5, 1029.5, and 1045.5) having multiple peaks in the TIC chromatogram. New peaks that were not observed with hydroxyl radical formed during photocatalytic oxidation (PCO) have been detected such as m/z 1045.5. The initially formed intermediates involved the oxidation of the unsaturated bonds of MC-LR especially the diene bonds located on the chain of the Adda amino acid. Subsequent intermediates implicated the oxidative cleavage of small functional groups (i.e., -COOH), up to the complete removal of the Adda chain. The electrophilic character of SO(4)(•-) is proven by the multihydroxylation of the aromatic ring. Toward the end of treatment, simultaneous oxidation of the Adda chain and the cyclic structure occurred without the formation of linear products.
本研究采用基于硫酸根自由基的高级氧化技术（AOTs）降解微囊藻毒素-LR（m/z 995.5），并鉴定了处理过程中形成的反应中间体。据我们所知，这是首次针对任何含有 SO(4)(•-)的蓝藻毒素进行降解和反应中间体鉴定的研究。串联质谱指定了 9 个（m/z）反应中间体的形成，其中 4 个（m/z 1011.5、1027.5、1029.5 和 1045.5）在 TIC 色谱图中有多个峰。在光催化氧化（PCO）过程中形成的羟基自由基未检测到新的峰，例如 m/z 1045.5。最初形成的中间体涉及 MC-LR 中不饱和键的氧化，特别是位于 Adda 氨基酸链上的二烯键。随后的中间体表明，小官能团（例如 -COOH）发生了氧化裂解，直到 Adda 链完全去除。SO(4)(•-)的亲电性通过芳环的多羟基化得到证明。在治疗结束时，Adda 链和环状结构同时发生氧化，而没有形成线性产物。
