A sensitive and selective amperometric immunosensor for chloramphenicol (CAP, IUPAC name: 2, 2-Dichloro-N-[2-hydroxy-1-(hydroxymethyl)-2-(4-nitrophenyl) ethyl] acetamide) detection based on magnetic nanocomposites modify screen-printed carbon electrode (SPCE) as a disposable platform was fabricated. Graphene sheets (GS)-Nafion (Nf) dispersed solution was first dropped on the SPCE and then Fe3O4-Au nanoparticles (GoldMag particles, GMP) coated bovine serum albumin-CAP (BSA-CAP) conjugates was absorbed on it with the aid of external magnetic fiel...