Purosphere column

The HPLC-photodiode array detection system (Shimadzu, Kyoto, Japan) was used for the detection and identification of MCs and their degradation products. The UV detection range was 200–300 nm. MC-RR, MC-LR, and MC-LF (Enzo Life Science, Lausen, Switzerland) were used as the standards. Separation of supernatant components was performed using a Purosphere column (125 × 3 mm, dp 5 µm, Merck, Darmstadt, Germany) with the mobile phase composed of acetonitrile (Merck, Burlington, VT, USA) and gradient-grade water for HPLC acidified with 0.05% trifluoroacetic acid (gradient 30–100%), at a flow rate 0.7 mL/min. MCs and their biodegradation products were identified on the basis of specific spectra and the time of elution compared with the spectra and elution times of standards. Each fresh MC standard used in the experiment, to prepare a calibration curve, and to identify MCs and their degradation products had one specific peak and spectrum.

An HPLC-photodiode array detection system (Shimadzu) was used for the detection and preliminary identification of MCs in crude cyanobacterial extracts, and in the extracts of samples used for experiments and collected after a seven-day exposure. The UV detection range was 200–300 nm. [D-Asp³]MC-RR, -RR, -YR, -HtyR, [D-Asp³]MC-LR, -LW, -LA, -LY, -WR, -LF (Alexis) were used as the standards. Separation of extract components was performed using a Purosphere column (125 × 3 mm, dp 5 μm, Merck) with the mobile phase composed of acetonitrile (Merck): Milli-Q water acidified with 0.05% trifluoroacetic acid (gradient 30–100%), at a flow rate 0.7 mL/min.