Picomole determination of vanillin in infant formula by molecularly imprinted polypyrrole nanowires/reduced graphene oxide-based electrochemical sensor

A molecularly imprinted polymer/reduced graphene oxide (MIP/RGO)-based electrochemical sensor was developed for determining vanillin (VAN). The sensing element of MIP/RGO modified electrode was fabricated by successive in-situ electrodeposition of RGO and molecularly imprinted polypyrrole nanowires on a bare glassy carbon electrode surface. The RGO was utilized for signal amplification and the molecularly imprinted polypyrrole nanowires was used for specific recognition of VAN. VAN was detected by square-wave voltammetry using the redox probe of potassium ferricyanide. Under the optimized conditions, the MIP/RGO-based electrochemical sensor exhibited an ultra-wide linear response range of 10 pM to 100 μM and ultra-low limit of detection of 5.4 pM for VAN with the advantages of simplicity, good reproducibility, high stability and excellent selectivity. The proposed electrochemical sensor could also be employed to monitor picomole quantities of VAN in infant formula samples with good recoveries.