C18-coated stir bar sorptive extraction combined with high performance liquid chromatography-electrospray tandem mass spectrometry for the analysis of sulfonamides in milk and milk powder

► C18-coated stir bar using PDMS-sol as adhesive glue was prepared and characterized. ► A new method of C18-coated SBSE-HPLC-MS/MS was developed to determine sulfonamides. ► Compared to PDMS, C18 shows good affinity to the polar/weak polar sulfonamides. ► The proposed method is sensitive, accurate, simple, rapid and low-cost. ► It can be applied to the analysis of compounds with different polarity.