▎ 摘　　要

The authors describe a screen-printed electrode (SPE) modified with a composite consisting of Mn3O4 microcubes and thin sheets of graphene oxide for use in amperometric determination of nitrite. The composite was prepared by a hydrothermal method, and its morphology, elemental composition, diffraction, impedance and electrochemical properties were studied. The modified SPE displays excellent electrocatalytic activity towards nitrite, and the oxidation peak current (measured typically at 0.70 V vs. Ag/AgCl) is related to the concentration of nitrite in the range between 0.1 and 1300 mu M, with a 20 nM detection limit. The method was successfully applied to the determination of nitrite in spiked samples of beef and water.