Disposable Electrochemical Ascorbic Acid Sensor Based on Molecularly Imprinted Poly(o-phenylenediamine)-Modified Dual Channel Screen-Printed Electrode for Orange Juice Analysis

An electrochemical biomimetic sensor was developed for fast and selective detection of ascorbic acid (AA) in orange juice samples via electropolymerizing o-phenylenediamine on the surface of a dual channel screen-printed carbon electrode (SPCE), which could achieve two repetitive measurements by using the same sample drop and improve test efficiency. The square wave voltammograms and scanning electron microscopy images indicated that the many imprinted cavities had formed in the AA-imprinted poly(o-phenylenediamine) film, which acted as a selective recognition element to determine AA by means of the matched size, shape, and orientation of the functional groups between the imprinted cavities and AA molecules. The response current of the imprinted sensor was linearly related to the concentration of AA in both lower concentration regions (0.45–13.52 μM) and higher concentration regions (13.52–409.10 μM), respectively. The detection limit was 0.11 μM based on the signal to noise ratio of 3. The sensor was applied to determine AA in commercial orange juice, and the result was in good agreement with that obtained by 2,6-dichlorophenol indophenol titration method. The fabrication of the sensor was simple and timesaving (<35 min for modifying two work electrodes). Together with portability and disposability of the AA-MIP/SPCE, the proposed sensor had widely potential applications in field test and analysis.