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TheScientificWorldJOURNAL
Volume 11 (2011), Pages 20-26
doi:10.1100/tsw.2011.17
Research Article

Comparative Studies on the pH Dependence of DOW of Microcystin-RR and -LR Using LC-MS

Gaodao Liang,1,2 Ping Xie,1 Jun Chen,1 and Ting Yu1

1Donghu Experimental Station of Lake Ecosystems, State Key Laboratory of Freshwater Ecology and Biotechnology of China, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
2Wuhan Centers for Disease Prevention and Control, Wuhan, China

Received 23 August 2010; Revised 13 November 2010; Accepted 7 December 2010

Academic Editor: Lars Sonesten

Copyright © 2011 Gaodao Liang et al.

ABSTRACT

Microcystins (MCs) are well known worldwide as hepatotoxins produced by cyanobacteria, but little is known about the physicochemical properties of these compounds. The dependence of the n-octanol/water distribution ratio (DOW) of MC-RR and -LR to pH was measured by high-performance liquid chromatography combined with mass spectrometry (LC-MS). There was a remarkable difference in such relationships between MC-RR and -LR. The log DOW of MC-LR decreased from 1.63 at pH 1.0 to -1.26 at pH 6.5, and stabilized between -1.04 and -1.56 at a pH of 6.5~12.0; log DOW of MC-RR varied between -1.24 and -0.67 at a pH of 1.00~4.00, and stabilized between -1.20 and -1.54 at a pH of 4.00~12.00. The difference of hydrophobicity in acidic condition between MC-RR and -LR is important, not only for the analytical method of both toxins, but perhaps also for understanding the difference of toxicity to animals between the two toxins.