Application of ionic-liquid supported cloud point extraction for the determination of microcystin-leucine–arginine in natural waters

A cloud point extraction method has been developed using an ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate, BMiM PF6) for the determination of a widely studied cyanotoxin (microcystin leucine–arginine, MCLR) in natural waters. Extraction parameters such as sample pH, extraction temperature, extraction time, the amount of ionic liquid and the amount of extraction volume were investigated and optimized to achieve the maximum extraction efficiency. The results obtained indicated a good linearity with the correlation coefficient of 0.995 over the range of 0.5–50 μg L−1. The relative standard deviation (RSD) of the method was 7.5% (n = 6). The calculated method detection limit was 0.03 μg L−1 (n = 6). The practical applicability of the technique was demonstrated by analyzing water samples (n = 9) collected from three different sites in local reservoirs.