A Facile Electrochemical Sensor Labeled by Ferrocenoyl Cysteine Conjugate for the Detection of Nitrite in Pickle Juice

• Main Authors: Xiao-Zhen Feng, Annaleizle Ferranco, Xiaorui Su, Zhencheng Chen, Zhiliang Jiang, Guo-Cheng Han
• Format: Article
• Language: English
• Published: MDPI AG 2019-01-01
• Series: Sensors
• Subjects: electrochemical sensor; nitrite; ferrocenoyl cysteine; screen-printed electrode; disposable
• Online Access: http://www.mdpi.com/1424-8220/19/2/268
• ISSN: 1424-8220

Simple and facile electrochemical sensors for nitrite detection were fabricated by directly depositing ferrocenoyl cysteine conjugates Fc[CO-Cys(Trt)-OMe]2 [Fc(Cys)2] or Fc[CO-Glu-Cys-Gly-OH] [Fc-ECG] on screen-printed electrodes (SPEs). The modified carbon electrodes were characterized by scanning electron microscopy (SEM), cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Results indicated that Fc-ECG/SPE sensor showed enhanced current response and a lower overpotential than Fc(Cys)2/SPE sensor for nitrite detection. Optimal operating conditions were estimated for nitrite detection by DPV. The concentration of nitrite showed a good linear relationship with the current response in the range of 1.0–50 μmol·L−1 and with 0.3 μmol·L−1 as the concentration for limit of detection. There were no interferences from most common ions. The development of this electrochemical sensor was used for nitrite detection in pickled juice with a R.S.D. lower than 2.1% and average recovery lower than 101.5%, which indicated that disposable electrochemical sensor system can be applied for rapid and precise nitrite detection in foods.