Magnetic ionic liquids as an efficient tool for the multiresidue screening of organic contaminants in river water samples

In this study, a multiresidue analytical methodology based on magnetic ionic liquid as extraction phase and dispersive liquid-liquid microextraction, was developed for the determination of organic contaminants in river water samples by high-performance liquid chromatography with diode array detection (HPLC-DAD). Experimental conditions were carefully optimized using univariate and multivariate designs. A simplex-lattice design was adopted for the optimization of disperser solvent, univariate planning was applied to pH optimization and a central composite design was used for the optimization of magnetic ionic liquid mass, extraction time and NaCl concentration added to the samples. The optimal extraction conditions were a mixture of acetonitrile/methanol 50:50 v/v as disperser solvent, pH adjusted to 6.0, 10 mg of magnetic ionic liquid, and extraction time of 180 s. The analytical parameters of merit were determined under the optimized conditions, and very acceptable results were achieved, with limits of detection ranging from 1.5 to 15 mu g L-1 and determination coefficients (R-2) higher than 0.992 for all 15 analytes. Precision varied from 8.6 to 17.8% and from 0.4 to 19.3% for interday (n = 9) and intraday (n = 3) assays, respectively. Relative recoveries varied from 56 to 123% in two aqueous samples, both collected in Camboriu city, Santa Catarina, Brazil.