Rapid determination of sulfonamide residues in pork by surface-modified hydrophilic electrospun nanofibrous membrane solid-phase extraction combined with ultra-performance liquid chromatography

This study aimed to rapidly determine 13 representative sulfonamide (SA) residues in pork by using a surface-modified hydrophilic polystyrene sulfonic acid (PSSA) electrospun nanofibrous membrane as the solid-phase extraction (SPE) pretreatment sorbent, followed by ultra-performance liquid chromatography (UPLC) analysis. The highly hydrophilic nature of PSSA nanofibrous membrane created by vacuum plasma treatment was characterized using Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM), water contact angle, and X-ray photoelectron spectroscopy (XPS) measurements. In the pretreatment procedures, 13 SA standards, which were spiked in the fatty pork samples, were extracted, enriched, and purified by the SPE procedure based on the principle of ion exchange with the sulfonic groups on the PSSA chains. Under the optimized conditions, the calibration curves of 13 SA compounds showed good linearities with correlation coefficients (r) of more than 0.99 in the range of 50.0-200 μg kg(-1). The mean recoveries of 13 SAs at the spiked concentrations of 50, 100, and 200 μg kg(-1) were in the range of 70.3-92.5 % with average RSDs (n = 6) of less than 15 % (except for sulfacetamide, 56.9-61.6 %). Compared with other pretreatment methods reported previously, less organic solvent (especially without degreasing the extract with n-hexane) was used in this time-saving SPE procedure, which avoids the possibility of emulsification and therefore enhances the recoveries. The developed and validated analysis method was sensitive, accurate, rapid, convenient, environmentally friendly, and was successfully applied for the detection of 13 SA residues in commercially available pork samples.