Objective: To optimize the solid-phase extraction method of isolation, purification and determination of intracellular microcystin-RR, -YR and -LR (MC-RR,-YR,-LR), algal samples were collected from Dianshan Lake, which is a major water source of Shanghai.
Methods: During extraction, Algal samples were treated with different solvent (5% acetic acid and 75% methanol), at different temperature (room temperature and 56 degrees C), centrifuge at 10000 x g, 30 min and 3500 rpm/min, 10 min, eluted with 80% methanol with or without trifluoroacetate acid(TFA). Further, gradient elution were employed to separate microcystins in high performance liquid chromatography (HPLC), the mobile phase consisted of aqueous acetonitrile and 0.05% TFA.
Results: When dried algae cells were extracted by 5% acetic acid, 56 degrees C water bath combined with centrifuge at 3500 rpm/min was an effective and simple method for the extraction of microcystin-RR, elutant contains TFA can markedly increase the yield of microcystins extraction; the concentration of microcystin-RR in nature algal samples was higher than MC-LR and MC-YR.
Conclusion: The extraction efficacy of MC-YR and -LR is higher in 75% methanol aqueous and eluted with 80% methanol containing 0.05% TFA, while the extraction efficacy of MC-RR is higher in 5% acetic acid.