A comprehensive study demonstrating the influence of the solvent composition on the phytotoxicity of compounds, as exemplified by 2,<scp>4‐D</scp>‐based <scp>ILs</scp> with a choline‐type cation

Background: Growing concern for the protection of the environment and existing ecosystems has resulted in increasing consid-eration of phytotoxicity tests as valid ecotoxicological indicators of the potential hazards of the use of ionic liquids (ILs) or anyother chemical. The objective of this study was to gain a detailed understanding of the influence of the solvent composition ofspray solutions on the phytotoxic effect of foliar application of ionic pairs with weak (choline 2,4-dichlorophenoxyacetate,[Chol][2,4-D]), medium (N-hexylcholine 2,4-dichlorophenoxyacetate, [C6 Chol][2,4-D]) and good (N-dodecylcholine2,4-dichlorophenoxyacetate, [C 12 Chol][2,4-D]) surface-active properties.Results: Experimental results unambiguously demonstrated that the biological activity of the test salt solutions, particularly[Chol][2,4-D] and [C 6 Chol][2,4-D], can be strongly affected by the addition of an organic solvent, such as methanol, ethanol,dimethylformamide (DMF) or dimethylsulfoxide (DMSO) compared to solutions in pure water. However, the observed tendencyis less pronounced for the compound exhibiting good surface activity, [C 12 Chol][2,4-D].Conclusions: The collected findings show that caution is warranted in the exploitation or modification of methodologies forassessing phytotoxicity to ensure the reliable interpretation of obtained results for environmental risk assessment or buildingquantitative structure–activity relationship (QSAR) models.