Polyimide‐coated magnetic nanoparticles as a sorbent in the solid‐phase extraction of polycyclic aromatic hydrocarbons in seawater samples

Magnetic polyimide poly(4,4′‐oxydiphenylene‐pyromellitimide) nanoparticles were successfully synthesized and developed for the solid‐phase extraction of polycyclic aromatic hydrocarbons in seawater samples. The aromatic rings of polyimide coating provided a good adsorption capacity (28.3–42.5 mg/g) for polycyclic aromatic hydrocarbons because of the π–π stacking interaction. The developed method was used as a simple, fast, and efficient extraction and preconcentration technique for the trace analysis of polycyclic aromatic hydrocarbons. The high chemical, physical and thermal stability, excellent reusability, and good magnetic properties are the merits of the sorbent. High preconcentration factors (41–63) were obtained. The sorbent was also characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive X‐ray spectrometry, transmission electron microscopy, and vibrating sample magnetometry. After optimizing several appropriate extraction parameters, the results indicated that the extraction recoveries of polycyclic aromatic hydrocarbons were in the range of 61.6–94.7%, with relative standard deviations between 2.9 and 5.4%, the calibration graph was linear in the concentration range of 1–100 μg/L (r > 0.9991) with limit of detection in the range of 0.15–0.19 μg/L (n = 3). Seawater samples were analyzed as real samples and good recoveries (68.5–99.5%) were obtained at different spiked values.