Development of a highly selective nickel cobalt oxide nanoparticles modified molecular imprinted polymer based sensor for detection of gallic acid in green tea

In this work, a low cost solution route for sensing gallic acid in green tea has been established using nickel-cobalt oxide nanoparticles (Ni/CoOX NPs) embedded gallic acid imprinted polymer. The Ni/CoOX NPs so synthesized are thoroughly mortared with the molecular imprinted polymer prepared by co-polymerization of polyacrylic acid and ethylene glycol dimethacrylate (EGDMA) on a graphite sheet. Ultra violet visible spectroscopic (UV-vis) analysis has been performed in order to confirm the template removal. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were employed for determining the electrochemical and analytical characteristics of the electrode. The electrode is found to be highly repeatable with relative standard deviation (RSD) value of 0.94% and the relative selectivity coefficient (RSC) of 79.16%. The sensing electrode has been subjected to five green tea samples. Principal component analysis (PCA) was performed on the obtained DPV data set to observe the discrimination ability of the electrode on the basis of gallic acid content in green tea. The separability index (SI) value for PCA score plot is found to be 38.15, indicating a clear distinction among the samples.