Simultaneous determination of sulfonamides in milk: In-situ magnetic ionic liquid dispersive liquid-liquid microextraction coupled with HPLC.

Four novel organic magnetic ionic liquids were synthesized and characterized. A new method of in-situ magnetic ionic liquid dispersive liquid-liquid microextraction coupled with HPLC was established to simultaneously separate, preconcentrate and determine trace amount of sulfonamides in milk samples for the first time. In this work, extraction procedure was free of volatile organic solvent. Extraction equilibrium was immediately achieved without further operation such as vortex shaking. Magnetic separation of two phases was effectively achieved by applying external magnetic field without need of centrifugation. Furthermore, only a very small amount of inorganic salts were generated. This is the first time to realize all these advantages in an analytical method. Under the optimal conditions, satisfactory enrichment factors, precisions, linear range and low limit of detection and quantitation were acquired. The validated method was successfully applied in the simultaneous analysis of 5 sulfonamides in real milk samples.