title: Comparative studies on the pH dependence of DOW of microcystin-RR and -LR using LC-MS.
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.
authors.affiliation: Donghu Experimental Station of Lake Ecosystems, State Key Laboratory of Freshwater Ecology and Biotechnology of China, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, PR China.
authors.forename: Gaodao
authors.initials: G
authors.lastname: Liang
authors.forename: Ping
authors.initials: P
authors.lastname: Xie
authors.forename: Jun
authors.initials: J
authors.lastname: Chen
authors.forename: Ting
authors.initials: T
authors.lastname: Yu
mesh_terms: D002851:Chromatography, High Pressure Liquid; D057927:Hydrophobic and Hydrophilic Interactions; D008387:Marine Toxins; D013058:Mass Spectrometry; D052998:Microcystins / Q000737:chemistry*
chemical_list: D008387:Marine Toxins; D052998:Microcystins; C063855:microcystin RR; C057862:cyanoginosin LR