Optimal strategies for determination of free/extractable and total microcystins in lake sediment

Analysis of intracellular and extracellular microcystin variants in sediments and pore waters by accelerated solvent extraction and high performance liquid chromatography-tandem mass spectrometry

“…Equilibrium was reached after 4 h at 4 C, which was consistent with that found by Chen et al [16]. Semi-dry sediment was extracted directly or first lyophilized (referred to as dry sediment) in order to allow direct comparison to current extraction methods [15][16][17]25,26]. Recoveries were compared by Student's t-test analysis at p < 0.05.…”

“…However, only four variants of similar chemistry have been tested thus far [15][16][17][18] and laboratory and field studies suggest differences in the adsorption properties of different microcystins [3,19,20]. Furthermore, no method has yet demonstrated the recovery of microcystins from intact cyanobacterial cells in sediments despite increasing evidence of the significance of this microcystin pool [7][8][9][10][11][12][13][14].…”

“…These recoveries were comparable to those of extracellular microcystins. Considering the fact that intracellular toxins can deposit onto sediment [7][8][9][10], be produced by living cells within sediment [11][12][13], and persist within deep sediment [14], the efficacy of our ASE to recover intracellular cyanotoxins from sediment material is a major advantage compared to currently available methods [15][16][17].…”

A sensitive method for the determination of total microcystins in water and sediment samples by liquid chromatography with fluorescence detection

“…Sediment and water samples containing natural MCs or spiked with MCs were oxidized by the Lemieux reagent according to Wu et al 11 Each test was conducted in triplicate. For sediment samples, 1 g of freeze-dried sediment was oxidized with 10 mL oxidation reagent containing 20 mg mL À1 sodium periodate (NaIO 4 ) and 4000 mg L À1 potassium permanganate (KMnO 4 ) for 1 h under weakly alkaline conditions (pH $ 9) unless otherwise specied.…”

“…However, the MMPB yields were only mentioned in four studies and the reported values were inconsistent. 3,11,17,19 On the other hand, the direct quantication of MMPB using HPLC with a UV detector was not sensitive enough.…”