An in situ ionic liquid dispersive liquid-liquid microextraction method for the detection of pyrethroids by LC-UV in environmental water samples

An in situ ionic liquid dispersive liquid-liquid microextraction (IL-DLLME) method was developed as a new approach for the detection of four pyrethroid pesticides in environmental water samples. The method is fast,simple,accurate and environmentally friendly. The hydrophobic ionic liquid,[C ₈MIM]-NTf₂,formed by the water-soluble ionic liquid [C₈MIM]Cl and the ion exchange reagent LiNTf₂ was used as the extraction solvent. The experimental parameters affecting the extraction efficiency,including the amount of the IL,the extraction and the centrifugation times and the salt concentration were investigated and optimized using an orthogonal array design (OAD). A suitable molar ratio of LiNTf₂ to [C₈MIM]Cl on the recoveries of analytes was determined after OAD optimization. The method showed a good linear response in the range of 0.5 to 500 μg L^-1 with correlation coefficients (R²) above 0.9998. The relative standard deviation (RSD) varied from 0.6 to 1.9%. The enrichment factor,the limit of detection and recovery ranged from 134 to 153,0.02 to 0.18 μg L^-1 and 89.7 to 95.6%,respectively. For water samples,the RSD ranged from 0.02 to 2.34% and the recovery ranges from 91.4 to 99.9%.