Highly sensitive square wave voltammetric sensor employing CdO/SWCNTs and room temperature ionic liquid for analysis of vanillin and folic acid in food samples

Abstract Vanillin and folic acid are two important food additives with high nutritional value. Also, the high levels of vanillin and folic acid have side effects, such as allergic reaction (for vanillin) and colonic or rectal cancer (for folic acid). This study describes the fabrication of a highly sensitive sensor for determination of vanillin in the presence of folic acid in food samples. The electro-oxidation of vanillin was studied at a carbon paste electrode modified with cadmium oxide nanoparticle decorated with single wall carbon nanotubes (CdO/SWCNTs) and 1,3-dipropylimidazolium bromide (DPIB) as a binder (CPE/CdO/SWCNTs/DPIB). The electrochemical behavior of vanillin at bare CPE and CPE/CdO/SWCNTs/DPIB were compared, suggesting that the CPE/CdO/SWCNTs/DPIB significantly enhances the electro-oxidation signal of vanillin. In the mixture containing vanillin and folic acid, the oxidation peaks potential for the two compounds were well separated from each other. The square wave voltammetric response for vanillin and folic acid are linear in the dynamic range 0.03–800.0 μM and 0.1–1200 μM, and limit of detection of 9.0 ± 0.1 nM and 0.06 ± 0.01 μM, respectively. The CPE/CdO/SWCNTs/DPIB has been successfully applied to the analysis of vanillin and folic acid in food samples.