Exposed zebrafish (Danio rerio) to imidazolium-based ionic liquids with different anions and alkyl-chain lengths.

Ionic liquids (ILs) were considered new "green solvents" in consideration of the low volatility. Since their inception, ionic liquids (ILs) have attracted widespread attention. However, ILs were not safe enough as what we thought. The toxicity of 1-ethyl-3-methylimidazolium ILs ([C2mim]R, R = Cl-, Br-, BF4-) and 1-alkyl-3-methylimidazolium bromine ([Cnmim]Br, n = 2, 4, 8, 10, 12) using 50% lethal concentration (LC50) were studied in the present study to enrich the toxicological information. Besides the LC50 values, the sensitivity test using potassium dichromate (K2Cr2O7) and residue determinations of the tested ILs were also performed. The sensitivity and dynamic changes of IL doses both catered for the stipulation that declared the accuracy of the toxicological test results, which illustrated that the alkyl-chain lengths contributed more than anions to the toxicity of the ILs described above to zebrafish. Additionally, the present study also enriched the toxicological information on imidazolium-based ILs to aquatic systems.