Extraction and analysis of microcystins RR and LR in cyanobacteria using a cyano cartridge

A new method for the extraction of microcystins RR and LR in cyanobacteria was developed using a cyano cartridge. Lyophilized cells (100 mg) were extracted with 5% (v/v) acetic acid. The extract was centrifuged and then the supernatant was applied to a CN cartridge. The cartridge that contained microcystins was rinsed with 5 ml of water and 5 ml of 0.5 M acetic acid, followed by 5 ml of 5% acetonitrile in water. Microcystins were finally eluted from the CN cartridge with 70% acetonitrile in water and were determined by HPLC. Better recoveries and chromatograms were observed than with ODS cartridges.