Abstract: Two new types of elastic porous silanized melamine sponges (MeS) were prepared by silylation reaction using octadecyltrichlorosilane (OTS) and N-[3-(trimethoxysilyl)propyl]ethylenediamine (ATS), which were respectively designated as OTS@MeS and ATS@MeS. The silanized sponges were used to develop a modified quick, easy, check, effective, rugged, and safe (QuEChERS) method that can quickly and efficiently separate interfering matrices from the extract through spontaneous solution infiltration and physical extrusion. In this study, an analytical method using the modified QuEChERS procedure combined with ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was established for the simultaneous determination of 49 antibiotic residues in pork. Samples were extracted with 10 mL of acetonitrile containing 0.1% acetic acid, and then salted out with 2.0 g of Na2SO4 and 0.5 g of NaCl. After centrifugation, a 1 mL aliquot of the supernatant was cleaned up with a mixture of OTS@MeS and ATS@MeS. The chromatographic separation was conducted on an Agilent ZORBAX Eclipse Plus C18 column with gradient elution using a mobile phase comprised of methanol and aqueous solution (methanol/water, 5:95, V/V) containing 0.1% formic acid and 5 mmol/L ammonium acetate. The qualitative and quantitative detection were performed by multiple-reaction monitoring (MRM) using an electrospray ionization source in the positive ion mode. The results showed that the correlation coefficients for all analytes were greater than 0.999. The matrix effects (ME) were in the range of −13.5%−10.9%. The limits of detection (LOQ) and quantitation (LOQ) were 0.1–10.0 and 0.3–33.3 μg/kg, respectively. The recoveries at three spiked levels ranged from 65.0% to 112.7%, with intra- and interday relative standard deviations (RSDs) of 0.3%–11.8% and 2.4%–18.4%, respectively. The developed method was simple, rapid, highly sensitive and accurate, and could be used for the efficient and rapid determination of the 49 antibiotics residues in pork.

Key words: silanized melamine sponge; ultra-high performance liquid chromatography-tandem mass spectrometry; pork; antibiotics