Analysis of imidazolium ionic liquids in biological matrices: A novel procedure for the determination of trace amounts in marine mussels

Imidazolium ionic liquids (ILs) are chemical compounds beginning to be used on a mass scale. Although their presence in the environment is usually treated as only potential threat, there are already first evidences that this has become a real case. Taking into account their increasing use it might be expected that this problem will also increase in the nearest future. Given that some of the imidazolium cations exhibit high potential for bioconcentration, it is likely that they will accumulate in the tissues of wild organisms. Thus, there is no doubt that monitoring the presence of these compounds in organisms from potentially contaminated waters will be needed. Therefore, the aim of our study was to develop and fully validate a novel and reliable analytical procedure for the determination of the mixture of imidazolium ILs in Mytilus trossulus mussels. For this purpose, different extraction techniques were tested such as: microwave-assisted extraction (MAE), accelerated-solvent extraction (ASE) and bullet-blender homogenization (HOMO). Finally, the proposed procedure is based on the application of MAE technique for the extraction of imidazolium cations and SPE technique using Oasis HLB cartridges for the purification of the obtained extracts and LC-MS/MS technique with QqQ analyzer for their final determination. Absolute recoveries of the proposed analytical procedure reached 71–90%. The developed procedure is characterized with low limits of quantification, at 50–100 ng g⁻¹ dry tissue and allows for reliable determination of trace amounts of the tested compounds in complex biological matrix. Matrix effects obtained for the optimized procedure ranged from 7.8 to 37.5%. As a result, this is the first study presenting the analytical procedure for the analysis of imidazolium ILs in aquatic animal tissues.