N-octyl-modified magnetite NPs for optimization of solid phase extraction for trace analysis of phenytoin in real samples

Phenytoin is an anti-seizure medication used to treat epilepsy, as well as to control arrhythmias (irregular heartbeat) and to treat migraine headaches and nerve pain. It is recommended to determine the amount of this drug in the blood to control the seizure and prevent its toxicity. In the present study, a sensitive and simple procedure based on the dispersive solid phase extraction was developed and validated for the determination of Phenytoin in plasma samples. Hydrophobic n-octyl-modified magnetic iron oxide NPs (IONPs) was employed as the sorbent. The studied drug was detected using high-performance liquid chromatography with a diode array detector. The parameters affecting the extraction efficiency such as pH of the sample, amount of sorbent, extraction time, salt addition, type and volume of the desorption eluent and desorption time were optimized. After the extraction procedure, magnetic nanoparticles (NPs) were easily separated from the aqueous solution by applying an external magnetic field without the need to filtration or centrifugation. The separation and preconcentration procedures were fast and completed in less than 6 min. Under optimized conditions, this method achieved a low limits of detection (3.0 ng mL-1), wide linear dynamic ranges (10 to 1000 ng mL-1), high enrichment factors (226), good correlation coefficients (r = 0.996), and good repeatability (6.7 to 7.3%). This method was used to analyze plasma samples with good efficiency (≥ 90). Finally, the proposed method is suitable for the analysis of phenytoin in plasma samples from epileptic patients for therapeutic drug monitoring purpose.