▎ 摘　　要

The authors describe a hybrid nanocomposite consisting of polypyrrole (PPy) nanospheres doped with p-toluenesulfonic acid (p-TSA) and deposited on sheets of reduced graphene oxide (rGO). The rGO sheets oxide were first coated with Fe3O4 particles, and pyrrole was then polymerized on their surface to obtain architecture of the type PPy/Fe3O4/rGO. Addition of p-TSA during polymerization leads to the formation of p-TSA-doped PPy to obtain doped-PPy/Fe3O4/rGO. The resulting nanocomposite was characterized by transmission electron microscopy, scanning electron microscopy, FTIR, X-ray diffraction spectrometry and X-ray photoelectron spectroscopy. The nanocomposite was placed on a glassy carbon electrode to give an electrochemical sensor for dopamine (DA) that has a fairly low operational voltage (0.3-0.6 V vs. SCE), a wide linear range (7.0 nM-2.0 mu M), a low detection limit (2.33 nM), and good selectivity for DA over ascorbic acid and uric acid. It gave satisfactory results in the determination of DA in spiked samples of urine and serum.