[Purification and identification of microcystin-RR]

An effective method based on the combination of solid phase extraction and gel chromatography to extract and purify microcystin-RR (MC-RR) from natural cyanobacteria bloom was developed. Thirty five gram natural cyanobacterial bloom scum was extracted with 70% aqueous methanol. After the methanol in the crude extract was removed by a rotary evaporator, the solid phase extraction was used for preliminary purification and concentration. And then 7.5 mL eluent was concentrated to 2 mL and loaded onto a Sephadex LH-20 gel chromatographic column for further purification. The eluate was collected by tubes and detected at 238 nm. The elution curve was plotted by tube numbers as X-axis and the absorbance at 238 nm as Y-axis. The purity and the spectral characteristics of the final extract were identified with high performance liquid chromatograph (HPLC) and spectrophotometer, respectively. A total of 3.65 mg of MC-RR with a final yield of 74. 1% was obtained, and the purity was more than 90% with characteristic UV absorption spectra at 238 nm.