An electrochemiluminescent biosensor for vitamin C based on inhibition of luminol electrochemiluminescence on graphite/poly(methylmethacrylate) composite electrode

A novel graphite/poly(methyl methacrylate) (graphite/PMMA) electrode was prepared in this paper. It was found that the developed polymer graphite paste electrode has some advantages in electrochemistry and electrochemiluminescence (ECL), such as high sensitivity, good reproducibility, quick and wide linear range of response to some biomolecules. The ECL behavior of luminol has been investigated in detail at the graphite/PMMA electrode, and vitamin C was found to be able to inhibit this ECL system. Based on which an inhibited ECL detection method has been developed for determination of vitamin C in this paper. The proposed method exhibited good reproducibility, wide-range linearity, high sensitivity and stability with a detection limit of 8.3 × 10⁻⁹ mol L⁻¹ (signal-to-noise ratio = 3) and linear response range of 2.5 × 10⁻⁸-1.0 × 10⁻⁴ mol L⁻¹. The relative standard deviation was 2.3% for 5 × 10⁻⁶ mol L⁻¹ vitamin C (n = 9). The possible mechanism for inhibition of luminol on graphite/PMMA electrode has also been proposed.