Synthesis of polyethylene glycol-grafted magnetic nanoparticles for the fast and efficient extraction of anabolic substances from human urine

Anabolic steroids and β-agonists are commonly prohibited substances found in doping control studies; therefore, the determination of anabolic substances in biological samples is crucial. To analyze the anabolic compounds in urine, an adsorbent, polyethylene glycol (PEG)-grafted magnetic nanoparticle material (Fe 3 O 4 @SiO 2 -PEG), with low toxicity and strong biocompatibility was prepared in this investigation. Compared to those of Fe 3 O 4 and Fe 3 O 4 @SiO 2 , the grafted PEG chains (approximately 5.4 wt.%) on the magnetic nanoparticles improved the extraction efficiencies by factors of 3.9–17.0 and 2.5–2.9, respectively, likely due to the electrostatic attraction and hydrogen bonding. To achieve maximum extraction efficiency, several extraction parameters were optimized, including the kind and volume of desorption solvent, pH, and the extraction and desorption time. The standard curves were linear within the range of 0.5–20 μg/L for methyltestosterone and trenbolone, and 0.02–5 μg/L for clenbuterol. The limits of detection for the three drugs were 0.01–0.12 μg/L. The limits of quantification were 0.02–0.40 μg/L. The levels of precision of the optimized method were assessed based on the respective intra- and inter-day and batch-to-batch relative standard deviations in the ranges of 3.2–5.2 % ( n = 5), 5.9–11.3 % ( n = 4), and 6.7–9.2 % ( n = 3). The Fe 3 O 4 @SiO 2 -PEG nanoparticles could exclude urine matrix interferences (matrix effect of 91.8–98.1 %) and achieve satisfactory recoveries (75.5–116.1 %), affording sensitive and accurate determination of trace anabolic substances in urine.