Study on Separation of Microcystins Using Polymethacrylate-Based Capillary Monolithic Column

Polymethacrylate-based monolithic column was prepared in 150 microm i. d. capillary column in situ using butylmethacrylate and ethylene dimethacrylate. The application of methacrylate monolithic column in capillary high performance liquid chromatography ( micro-HPLC) for separation of microcystins (MCs) with ultraviolet (UV) detection has been studied. The properties of the monolithic column could be easily tailored by altering the preparation conditions. For the good reproducibility in preparation of monolithic column, this method could be used for the analysis of samples in practical. The effects of composition of mobile phase, pH value, concentration of the buffer, and the flow rate of the mobile phase on the separation of microcystins were investigated. The optimum separation for microcystins, MC-LR, MC-YR, and MC-RR, was achieved with a gradient elution of mobile phase A (0. 01 mol/L phosphate buffer, pH 2. 5 ) and mobile phosphate B (acetonitrile). The standard microcystins could be baseline-separated within 9 min. The limits of detection (LODs) (S/N = 3) for three standard microcystins were in the range of 0. 80 - 1. 03 mg/L. The intra-day and inter-day precisions of the method were obtained with the values of relative standard deviation less than 1. 0% and 2. 0%, respectively. This method was successfully used to analyze bloom samples and laboratory-cultured samples of cyanobacteria after performing solid phase extraction (SPE) using C18 cartridges for preconcentration. The whole procedure provided low LODs for MCs, e. g. the LOD for MC-LR was found to be 420 ng/L. This family of microcystin is analyzed by VL-HPLC using methacrylate monolithic column for the first time. It is shown that this method is promising in the routine analysis of microcystins in water samples in practical.