Microextraction by packed sorbent (MEPS) is a miniaturized form of SPE that was introduced in 2004 [1]. Graphene, a two-dimensional carbon based material, has attracted great interest in a wide range of applications including separation science due to its unique properties. Recently, polymeric materials have been widely used as sorbents for solid phase extraction. Adding graphene into polymers can improve their mechanical strength as well as the extraction capacity. This is the first study to use Polyacrylonitrile/Graphene Oxide (PAN/GO) nanofibers as an adsorbent in the MEPS technique in combination with Polystyrene (ENV+). The method was applied for the extraction of local anesthetics (lidocaine, prilocaine) and their metabolites from human plasma samples, and finally their analysis by LC-MS/MS.