Polyimide nanosheets based magnetic solid-phase extraction for the extraction of parabens from cosmetic samples...

This study introduces a novel magnetic composite based on polyimide nanosheets (Fe₃O₄@PINSs), designed for the highly efficient extraction of parabens from cosmetics. The composite was fabricated by combining Fe₃O₄ nanoparticles with polyimide nanosheets, yielding a material with excellent magnetic responsiveness (21.3 emu/g) and a high surface area (141 m²/g), both of which enhance separation and adsorption performance. The Fe₃O₄@PINSs composite was employed as the adsorbent in a magnetic solid-phase extraction (MSPE) protocol targeting six prevalent parabens in cosmetics, followed by gas chromatography-mass spectrometry (GC-MS) detection. A comprehensive study was carried out to optimize critical extraction and desorption parameters, including adsorbent dosage, extraction time, ionic strength, pH, desorption solvent selection, solvent volume, and desorption time. Under the optimized conditions, the Fe₃O₄@PINSs-based MSPE/GC-MS method exhibited a wide linear range (0.1-100 μg/L or 0.2-100 μg/L), high sensitivity (limits of detection of 0.037-0.077 μg/L), and good reproducibility (relative standard deviations ≤ 9.6%, n = 3). The calculated enrichment factors were between 15 and 19. When applied to real cosmetic samples-including hand creams, facial cleansers, and moisturizing lotions-the method provided reliable results, with recoveries ranging from 82.8% to 114.7%. Compared with previously reported methods, the proposed method shows comparable or better performance, with the notable advantage of a short extraction time (5 min). These findings suggest that the Fe₃O₄@PINSs composite has great potential as an adsorbent material in MSPE. The developed method is suitable for routine monitoring of parabens in cosmetic products, offering advantages of simplicity, rapidity, high sensitivity, accuracy, and precision.