A magnetic poly (methacrylic acid-co-ethylene glycol dimethacrylate) copolymer for extraction of anticonvulsants from saliva followed by high performance liquid chromatography analysis.

Neurological diseases like epilepsy are commonly treated with anticonvulsants, and the dosage control of these medications has been carried out with therapeutic biomonitoring, mainly in blood. Saliva is a less invasive sample, and its drug concentration is proportional to the blood fraction concentration not bound to the proteins, making it an important alternative to blood. Therefore, this study describes the synthesis of a magnetic poly (methacrylic acid-co-ethylene glycol dimethacrylate) copolymer (M-CP) and its use in magnetic dispersive solid phase extraction of primidone (PMR), phenobarbital (PB), phenytoin (PHT), and carbamazepine (CB) from saliva, followed by their determination by high performance liquid-chromatography. M-CP was synthesized in 4 steps and the material was characterized by infrared spectroscopy, scanning electron microscopy, zeta potential, and thermal analysis. The sample preparation protocol was optimized by central composite rotatable design and the optimal conditions were obtained for pH 5.78, 12.8 mg of M-CP, and 2.18 mL of diluted saliva. In the adsorption studies, the Avrami and Jovanovic models demonstrated the best fit for describing the adsorption kinetics and isotherm, respectively. The equilibrium time was reached in 60 min, and 10.96 mg g-1 was the maximum adsorption capacity. The developed method was linear (R2 > 0.99) in the range of 2 to 30 mg L-1 for PMR and PB, 1 to 20 mg L-1 for PHT, and 1 to 30 mg L-1 for CBZ. Precisions were obtained in the range of 1.35 to 19.44 %, and accuracy from -14.92 % to 18.83 %. The limits of detection ranged from 0.48 to 1.30 mg L-1, while the limits of quantification were lower than the therapeutic levels of each drug, being suitable for the method application. The developed method is simple, fast, and requires few amounts of saliva, sorbent, and solvents, being a good alternative for the therapeutic biomonitoring of anticonvulsants in saliva samples.