Electrochemical detection of quinoline yellow in soft drinks based on layer-by-layer fabricated multi-walled carbon nanotube

A novel modified electrode based on multi-walled carbon nanotubes was fabricated by alternatively depositing poly (diallyldimethylammonium chloride) functionalized MWCNT (PDDA-MWCNT) and poly(sodium 4-styrenesulfonate) functionalized MWCNT (PSS-MWCNT) via a solution based layer-by-layer (LbL) self-assembly method followed by calcination, and applied for the electrochemical detection of quinoline yellow. The electrode modification process was monitored by UV-vis spectroscopy which showed the linear growth of the film with the bilayer number. The electrocatalytic activity of MWCNT modified electrode towards oxidation of quinoline yellow was evaluated using cyclic voltammetry and amperometric method. Under the optimal conditions, the oxidation peak current was proportional to quinoline yellow concentration in a wide range between 0.02 and 10 μM, and the detection limit was 0.004 μM (S/N = 3). In addition, the fabricated electrode also displayed excellent reproducibility and stability, and employed to determinate quinoline yellow in soft drinks.