Cobalt oxide nanocrystals anchored on graphene sheets for electrochemical determination of chloramphenicol

This study demonstrates the hydrothermal synthesis of cobalt oxide (Co3O4) nanocrystals on reduced graphene oxide (rGO) which is further utilized to construct an electrochemical sensing scaffold for precise determination of chloramphenicol (CP). CP is an antibiotic used for the treatment of typhoid fever and infections including salmonellosis. Due to its antibacterial property, low cost and availability it was extensively used in the fields of agriculture, but its presence in animal derived food products create detrimental effects on consumers. Therefore it is important to monitor the level of CP in different food products. The formation of Co3O4 on rGO (Co3O4@rGO) is characterized with FT-IR, XRD, TEM and SEM techniques. The working electrode is fabricated by drop coating the catalyst (0.1% Co3O4@rGO in DMF) on glassy carbon (GC) electrode (symbolized as GC/Co3O4@rGO) and further used for electrochemical sensing of CP with cyclic voltammetry (CV), amperometry and differential pulse voltammetry (DPV) techniques. The calibration curve for the determination of CP through CV shows a linear range from 1 to 2000 mu M with two different slopes. Sensitivity of the CP determination and limit of detection (LOD) are calculated to be 1.32 mu A mu M cm(-2) and 0.55 mu M, respectively. Further the sensing scaffold, GC/Co3O4@rGO is successfully applied for the CP determination present in real samples like milk products.