关键词: 多孔有机聚合物, 固相萃取吸附剂, 磺胺类药物, 兽药残留, 超高效液相色谱-四极杆飞行时间质谱

Abstract: In this study, a porous organic polymer (POP) material with significant potential was developed, and an analytical method with high recovery and low detection limit was established, which can achieve the efficient extraction and analysis of trace sulfonamides (SAs) in food samples. POPs materials have the advantages of high specific surface area, excellent thermal and chemical stability, high designability and modifiability. In this study, we synthesized a POP material, TAPA-TFPB, using tri(4-aminophenyl) amine (TAPA) and 1,3,5-tri(4-formylphenyl) benzene (TFPB) as starting materials under acetic acid-catalyzed conditions. The material was used as a solid-phase extraction (SPE) adsorbent. A method combining solid-phase extraction with ultra-high-performance liquid chromatography-quadrupole time-of-flight tandem mass spectrometry (UHPLC-QTOF-MS/MS) was established to analyze five trace-level SAs in animal-derived foods. The structure and composition of the material were characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). These characterization results confirm the successful preparation of the material. The SEM images revealed that TAPA-TFPB exhibits a hierarchical flower-like structure formed by the assembly of nanorods, with a size of 500-1 000 nm. The XRD pattern shows a wide diffraction peak in the range of 5-40°, indicating an amorphous structure, and the specific surface area of the material is calculated to be 14.2 cm²/g. FT-IR analysis showed that the characteristic absorption peak of the imine bond (C=N) appeared at 1 617 cm^-1, which proved that TAPA-TFPB was successfully formed. At the same time, a weak residual aldehyde group (C=O) signal was detected at 1 690 cm^-1. TGA analysis indicated that this material exhibits excellent thermal stability. At 460 ℃, the mass retention rate exceeds 95%, and at 900 ℃, the residual mass remains as high as 58.6%. Subsequently, the parameters affecting the SPE efficiency were optimized. These parameters included the TAPA-TFPB adsorbent dosage, sample pH, washing solvent, elution solvent, elution volume, sample volume, and extraction solvent. The optimal experimental conditions were ultimately determined. The regeneration capability and reusability of the material were also evaluated. The experimental results showed that the optimal TAPA-TFPB dosage was 40 mg, and efficient extraction could be achieved without pH adjustment during sample pretreatment. The samples were extracted with acetonitrile, washed with water and eluted with 2 mL of methanol. In multiple consecutive extraction cycles, the recovery rates of all five SAs remained stable, except for a slight decrease in the recovery rate of sulfapyridine (SPD). This indicates that TAPA-TFPB possesses excellent regenerative capacity and stable cyclic performance. The method validation demonstrated good linearity (R²≥0.990) for five SAs across the 1-200 µg/L concentration range, with low LOD (≤0.31 µg/kg). The spiked recovery tests were conducted on real samples (chicken meat, pork, and milk) at three levels (5, 50, and 100 µg/kg). The spiked recoveries ranged from 71.5% to 115.7%. The intra-day RSDs ranged from 3.7% to 16.6%, while the inter-day RSDs were from 0.1% to 9.4%. This study developed a porous POPs material with significant potential, enriching the range of SPE adsorbents. An analytical method was established featuring high recoveries, low detection limits, and enables efficient extraction and analysis of trace SAs in food samples. This study can provide new theoretical support for the application of POPs materials in the pretreatment of veterinary drug residues.

Key words: porous organic polymers (POPs), solid phase extraction (SPE) adsorbent, sulfonamides (SAs), veterinary drug residues, ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-QTOF-MS/MS)