Highly-sensitive and rapid determination of sunset yellow using functionalized montmorillonite-modified electrode

•Highly-sensitive and rapid analytical method was developed for sunset yellow.•CTAB functionalized MMT-Ca was used to enhance detection sensitivity remarkably.•It was demonstrated with drink samples, and the accuracy was tested by HPLC. Montmorillonite calcium (MMT-Ca) was functionalized with cetyltrimethylammonium bromide (CTAB) via cationic exchange effects. Compared with MMT-Ca, the resulting CTAB functionalized MMT-Ca (CTAB/MMT-Ca) greatly increased the oxidation peak current of sunset yellow, indicative of strong signal enhancement effects. The oxidation mechanism was studied, and one electron was transferred during the oxidation of sunset yellow. The influences of pH value, mass ratio of CTAB to MMT-Ca, amount of CTAB/MMT-Ca, and accumulation time were studied on the oxidation signal of sunset yellow. As a result, a highly-sensitive, rapid and simple electrochemical method was newly developed for the determination of sunset yellow. The linear ranger was from 2.5 to 200nM, and the detection limit was as low as 0.71nM after 1-min accumulation. This method was applied in soft drink samples, and the detected results consisted with the values that obtained by high-performance liquid chromatography.