Determination of 19 sulfonamides residues in pork samples by combining QuEChERS with dispersive liquid-liquid microextraction followed by UHPLC-MS/MS.

A new simple and rapid pretreatment method for simultaneous determination of 19 sulfonamides in pork samples was developed through combining the QuEChERS method with dispersive liquid-liquid microextraction followed by ultra-high performance liquid chromatography with tandem mass spectrometry. The sample preparation involves extraction/partitioning with QuEChERS method followed by dispersive liquid-liquid microextraction using tetrachloroethane as extractive solvent and the acetonitrile extract as dispersive solvent that obtained by QuEChERS. The enriched tetrachloroethane organic phase by dispersive liquid-liquid microextraction was evaporated, reconstituted with 100 μL acetonitrile/water (1:9 v/v) and injected into an ultra-high performance liquid chromatography with a mobile phase composed of acetonitrile and 0.1% v/v formic acid under gradient elution and separated using a BHE C18 column. Various parameters affecting the extraction efficiency were investigated. Matrix-matched calibration curves were established. Good linear relationships were obtained for all analytes in a range of 2.0-100 μg/kg and the limits of detection were 0.04-0.49 μg/kg. Average recoveries at three spiking levels were in the range of 78.3-106.1% with relative standard deviations less than 12.7% (n = 6). The developed method was successfully applied to determine sulfonamide residues in pork samples.