When ionic liquids (ILs) first came into use, we thought that they were safe. However, upon further investigation, researchers found that ILs are not harmless. In this study, the model soil organism, earthworms (Eisenia foetida), were used to study the acute toxicity of imidazole nitrate ionic liquids with varying chain lengths from 2 to 12. The experiment used two different methods, a filter paper contact test (48 h) and an artificial soil test (14 days), to determine the toxicity. These results demonstrated that the toxicity increased with the length of carbon chains until C8 and that the cut-off effect occurred at 1-octyl-3-methyl imidazole nitrates.Then, the toxicity began to increase again. At the same time, the concentrations of [C10mim]NO3 and [C12mim]NO3 were determined by high performance liquid chromatography and demonstrated that ILs were stable throughout the experiment. The present study revealed the acute toxicity of ILs with varying chain lengths.
Keywords: Artificial soil; Concentration measure; Cut-off effect; Filter paper contact; LC50.