Dispersive micro-solid-phase extraction using carbon-based adsorbents for the sensitive determination of verapamil in plasma samples coupled with capillary electrophoresis.

A dispersive micro-solid-phase extraction procedure coupled with capillary electrophoresis ultraviolet detection was developed for determination of verapamil in plasma samples. Graphene oxide/polydopamin was synthesized by a one-step polymerization method, and graphene oxide/Fe3 O4 (magnetic graphene oxide) nanocomposite was prepared by coprecipitation method. Moreover, they were fully characterized. The use of hazardous and water-immiscible solvents was scaled down, and only 500 μL of acetone was required as the desorption solvent. The detector response concentration plots were linear in the range of 5-500 ng/mL, and the proposed method was validated according to guidelines. The precision and accuracy were less than 15%. Dispersive micro-solid-phase extraction method provides a rapid, environmentally friendly, and sensitive analysis for the verapamil in patient plasma samples, which is adequate for therapeutic drug monitoring and pharmacokinetic studies.