▎ 摘　　要

A new sorbent was synthesized for restricted-access matrix solid phase extraction (RAM-SPE) of the diabetes drugs metformin (MET) and glimepiride (Glim). Mesoporous silica layers were placed on Fe3O4-magnetized graphene modified with sulfo-functionalized pore walls (denoted as magG@mSiO(2)-SO3H composites). The composites have a large specific surface (173m(2)g(-1)), appropriate pore sizes (typically 3.7nm), and sulfo-functionalized pore walls. Magnetic separation can be accomplished within 10s. The unique properties of the composites allow both MET and Glim to be selectively and quickly extracted from plasma sample. Following magnetic separation and elution by 50% aqueous acetonitrile with 4% ammonium solution, the two drugs were quantified by LC-MS/MS analysis. The assay has high selectivity, good linearity (2.5-4000ng center dot mL(-1) for MET and 0.02-1600ng center dot mL(-1) for Glim), a low detection limit (as low as 60pg center dot mL(-1) for MET and 1pg center dot mL(-1) for Glim), excellent recovery (above 92.2%), and good precision (RSDs <12%). The method was successfully applied in a pharmacokinetic study in beagle dogs.