CTAB functionalized graphene oxide/multiwalled carbon nanotube composite modified electrode for the simultaneous determination of ascorbic acid, dopamine, uric acid and nitrite

• CTAB modified graphene oxide (CTAB-GO) was synthesized.
• The electro-oxidations of AA, UA and nitrite were catalyzed by CTAB-GO.
• CTAB-GO/MWNT nanocomposite modified GCE was fabricated.
• Overlapping peaks of AA, DA, UA and nitrite were resolved on CTAB-GO/MWNT.

We have developed hexadecyl trimethyl ammonium bromide (CTAB) functionalized graphene oxide (GO)/multiwalled carbon nanotubes (MWNTs) modified glassy carbon electrode (CTAB-GO/MWNT) as a novel system for the simultaneous determination of dopamine (DA), ascorbic acid (AA), uric acid (UA) and nitrite (NO2−). The combination of graphene oxide and MWNTs endow the biosensor with large surface area, good biological compatibility, electricity and stability, high selectivity and sensitivity. In the fourfold co-existence system, the linear calibration plots for AA, DA, UA and NO2− were obtained over the range of 5.0–300 μM, 5.0–500 μM, 3.0–60 μM and 5.0–800 μM with detection limits of 1.0 μM, 1.5 μM, 1.0 μM and 1.5 μM, respectively. In addition, the modified biosensor was applied to the determination of AA, DA, UA and NO2− in urine samples by using standard adding method with satisfactory results.