Optimization of total microcystin determination in sediment samples based on Lemieux oxidation and HPLC fluorescence detection

摘要

@@Microcystins (MCs) are a family of related cyclic hepatotoxic heptapeptides, of which more than 80 types have been identified. Oxidation of MCs causes the cleavage of MCs’ Adda amino to form 2-methyl-3-methoxy-4-phenylbutanoic acid (MMPB), which has been exploited to enable analysis of the entire family. In order to develop a highly effective analytical method for detecting MMPB as an oxidation product for total MC determination in natural sediment samples, the oxidation reaction conditions for the formation of MMPB were optimized and a labeling regent, 1,2-benzo-3,4-dihydrocarbazole-9-ethyl-p-toluenesulfonate (BDETS) was used for higher sensitive detection of MMPB. This investigation provided an insight into the influence of the oxidation reaction conditions (concentration of the reactants, temperature and pH) on the yield of MMPB and the results indicated that the optimized procedure could be carried out at a high dose of permanganate (~50 mM) in saturated periodate solution (~100 mM) at ambient temperature (~20 ℃) under alkaline conditions (pH ~9) over a period of hours (1~4 h).