Analysis Of The Microcystins In Fresh Water Aquatic Animals

As the pollution and global warming became more and more serious, cyanobacteria occurs more frequently and extensively in recent years. Many cyanobacterial species have the ability to produce cyclic hepatotoxic peptides called microcystins (MCs), which are not only responsible for threatening drinking-water but also aquatic animals. Monitoring of microcystin LR (MC-LR) in fish and other aquatic animals is important for evaluating the potential risk for human consumption.1. Microcystins (MCs) in dry cyanobacterial obtained from Dianchi Lake were extracted with 5% acetic acid and the main extraction steps included magnetic stirring, centrifugation, and filtration. The crude extraction of MCs was further purified by passing through cartridges with macroporous resin D101, which was proved to have the highest recovery comparing to other types of resins tested. The adsorbed MCs were eluted from the cartridge with ethanol-water solutions and three major types of MCs, i.e., MC-RR, MC-YR and MC-LR were obtained with purities of 82.6%, 82.1% and 62.5% respectively.The best drying method was roasting. pH 3 was the optimized condition for the resin D101 on MCs adsorption. This study provides a safe, efficient and cheap isolation and purification method for MCs.2. A solid phase extraction (SPE) with liquid chromatography ultraviolet spectrometry (LC/UV) method has been developed to identify and quantify MC-LR in aquatic animals. The extracted procedure was optimized by comparing different extracted solvents, homogenized types and time. The optimum performance method was obtained with following procedures,i.e., 85 % methanol was used as the extractant and samples were homogenized for 1h with continuous shaking at 25℃. The recoveries were increased from 70 % to 80 % with the increase of the amount of MC-LR standard additional from 0.17μg/g to 3.33μg/g. The method exhibits highly consistent recoveries with the RSDs better than 5%. The recovery study showed that blowing to 1mL ML-LR in MeOH by nitrogen stream was better than that to dryness according as the recoveries were 70%～80% and 35%～60%, respectively. The limit of detection was 0.067μg/g. This analytical method presented a simple and rapid procedure for determining MC-LR, and could apply to most of aquatic animals.