Abstract: Nano-Fe2O3-modified graphite electrode was prepared and used as a new potentiometric sensor for the detection of ascorbic acid. The properties, determination conditions and factors of this potentiometric sensor were explored. Results indicated that the linear range of this sensor in phosphate buffer solution with pH 6.5 ranged from 1.0 × 10-6 to 1.0 × 10-3 mol/L (r = －0.9969) with－30.2 mV/pC slope and 8.9 × 10-7 mol/L detection limit. This sensor has been used for determining ascorbic acid in orange juice and vitamin C tablets with satisfactory results. 

Key words: Nano-Fe2O3, modified electrode, potentiometric sensor, ascorbic acid