Silica-Functionalized Nano-Graphene Oxide Composite as Potent-Dispersive Solid-Phase Extraction Adsorbent of Methylphenidate from Urine Samples

Abstract

Silica-functionalized nano-graphene oxide composite (SFNGC) was successfully synthesized by a simple and cost-effective method. The resulted material was characterized and used as dispersive solid-phase extraction (DSPE) adsorbent for selective extraction of methylphenidate from urine media coupled with high-performance liquid chromatography ultra-violet detector. The DSPE adsorbent was dispersed thoroughly in the media through hydrophilic functional groups on the surface and could interact well by methylphenidate according to electrostatic reaction. Factors affecting the extraction process were studied by one-parameter-at-a-time method. The summery of the optimized parameters is as follows: 400 µL of methanol, urine pH value of 9, 60 mg of SFNGC, 4000 stirring rate, 20 min of extraction period and 25 min of desorption time and 6 mL of urine volume were the optimized as extraction parameters. By profiling the calibration curve, the linear range of the method was regarded as 100–2000 ng/mL. Limit of detection for the new method was 30 ng/mL. The analysis of addicted subjects with the proposed method confirmed the capability of the method in different laboratories.