Development and application of vitamin C sensor with synergistic sensitization of gold nanoparticles and multi walled carbon nanotubes

Objective  A low-cost and high response electrochemical sensor for vitamin C was developed to realize the rapid detection of vitamin C content in fruits and vegetables.

Method  MWCNTs/Au/PGE electrode with strong catalytic response to vitamin C was constructed by modifying gold nanoparticles and multi walled carbon nanotubes on pencil lead electrode. The electrode was characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy and cyclic voltammetry. The application range and optimal condition of the electrode pH were determined by differential pulse voltammetry. The standard curve and equation were established by time-current method to realize rapid detection. Finally, the vitamin C content of tomato was detected by standard addition recovery method.

Result  The vitamin C electrochemical sensor based on MWCNTs/Au/PGE electrode could accurately determine the vitamin C content in the range of pH 4–8, and its performance was the best when pH was 5. During rapid detection, the detection mass fraction range was 1–500 μg/g, sensitivity up to 0.244 μA·(μg/g)⁻¹·cm⁻². The interference rates of the sensor to glucose, malic acid and citric acid were less than 1.77%, and the relative standard deviation (RSD) measured by the same sensor for many times was 2.7%. The vitamin C content of tomato sample was 69.42 μg/g, the recovery was 109%–113%, and the RSD was less than 2.26%.

Conclusion  MWCNTs/Au/PGE electrode has the advantages of simple preparation process, low cost, high sensitivity, wide measurement range, strong stability and anti-interference. It provides a new idea for the rapid detection of vitamin C in fruits and vegetables.