High-performance Liquid Chromatography-tandem Mass Spectrometry for the Determination of the 21 Sulfonamide Residues in Eriocheir sinensis

The method of simultaneous determination of twenty commonly used sulfonamide residues in Eriocheir sinensis by high performance liquid chromatography-electro spray tandem mass spectrometry(HPLC/ MS/MS) is described.Sulfonamide residues were extracted from homogenized tissue with acetonitrile and dichloromethane.A part of the extract was taken and then dried by nitrogen.The residues were dissolved into 1 mL mobile phase and defatted with n-hexane(saturated by acetonitrile).The 21 analytes were separated on ZORBAX Eclipse XDB-C8 Column with mobile phases containingmethanol and 0.2% acetic acid and finally determined by electrospray ionization tandem mass spectrometry(ESI-MS-MS).A linear gradient eluting pro-gram of methanol from 30% to 80%(V/V) was employed at a flow rate of 0.2 mL/min in 35 minutes.Analytes confirmation were performed using multiple reaction monitoring(MRM) with one precursorion and two product ions as identifiers.The quantitative limit of method was 5 μg/kg.Recoveries tested by standard addition method were in the range of 71.8%-106%,RSDs were in the range of 0.44%-10.1% at a spiking level from 4 μg/kg to 40 μg/kg(n= 6).