All fractions obtained from the supernatant of M. aeruginosa PCC 7804, M. aeruginosa Sciento and N.
spumigena were analyzed by HPLC. The chromatograms of standard microcystin LR (retention
time: 24.04 min) and nodularin (retention time: 24.04min) are presented in the Figure 2 and 3. It was found that microcystin LR was present in 25%, 50% and 75% aq. methanol fraction of M. aeruginosa PCC
7804 and 50% aq. methanol fraction of M. aeruginosa Sciento. The 50% aq. methanol fraction of N. spumigena contained nodularin. Comparing the chromatographs with standard microcystin LR and
nodularin it is assumed that 25%, 50% and 75% aq. methanol fraction of M. aeruginosa PCC7804
contained approximately 22.6, 157 and 31.2 ìg/mL toxins, respectively, while 50% aq. methanol fraction
of M. aeruginosa Sciento and 50% aq. Methanol fraction of N. spumigena contained 10 and 28.2
ìg/mL toxins. Other fractions were found to contain an average amount of toxins.