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. 2017 Apr 6;9(4):129. doi: 10.3390/toxins9040129

Figure 5.

Figure 5

Effect of acidified methanol concentration on the adsorption of selected microcystins to polypropylene pipette tips. Individual samples were subjected to eight successive pipetting steps. Representative congeners (double-, single-, non-arginated) include MC-RR (A); MC-LR (B); MC-RA (C); and MC-LA (D). Solvents were acidified by adding 0.1% (v/v) of formic acid (FA) to the individual solvents. Controls were performed without using polypropylene pipette tips (0 pipetting steps) in triplicate. Small letters represent the significance levels at the individual pipetting steps: a, water vs. 20% MeOH; b, water vs. 40% MeOH; c, water vs. 60% MeOH; d, water vs. 80% MeOH; e, 20% MeOH vs. 40% MeOH; f, 20% MeOH vs. 60% MeOH; g, 20% MeOH vs. 80% MeOH. Significance levels are represented by the repetition of the letters, e.g., a, p < 0.05; aa, p < 0.01; aaa, p < 0.001.