Carbon Paste Electrode Modified with TiO2/Fe3O4 /MWCNT Nanocomposite and Ionic Liquids as a Voltammetric Sensor for Sensitive Ascorbic Acid and Tryptophan Detection

A carbon paste electrode modified with TiO2/Fe3O4/MWCNT nanocomposite and ionic liquids (TFMWCNT/IL/CPE) was employed for the simultaneous determination of ascorbic acid (AA) and tryptophan (TRP). The TFMWCNT/IL/CPE displayed excellent electrochemical catalytic activities toward AA and TRP oxidation compared with bare CPE. In the differential pulse voltammetry technique, both AA and TRP gave sensitive oxidation peaks at 270 and 700 mV respectively. Under the optimized experimental conditions, AA gave linear responses over range of 2.5 to 100.0 μM. The lower detection limit was found to be 1.13 μM for AA. The investigated method showed good stability, reproducibility, and repeatability for determination of AA and TRP in pharmaceutical samples.