Determination of Ferulic Acid Based on L-Cysteine Self-assembled Modified Gold Electrode Coupling Irreversible Biamperometry

L-cysteine self-assembled monolayers have been fabricated on the surface of gold electrode (L-Cys/SAM-Au/CME), and also the electrochemical behaviors of ferulic acid on the modified electrode were investigated. The self-assembled monolayer modified electrode was applied to the flow-injection irreversible biamperometric analysis. The irreversible system was composed of electrocatalytic oxidation of ferulic acid on L-cysteine-gold-modified electrode and reduction of permanganate at the other bare gold electrode. This novel method was used to establish the flow-injection irreversible biamperometric system under the applied potential difference of 0 V. In the 0.05 M sulfuric acid, the oxidative peak current increases linearly with the concentration of ferulic acid in the range of 5 × 10−7−8 × 10−5 M, linear regression equation: i(nA) = 4.16 × 107C + 50, and in the range of 1 × 10−4−1 × 10−3 M, linear regression equation: i(nA) = 5.6 × 106C + 300 with a sampling frequency of 80 samples per hour. The detection limit for ferulic acid is 1.2 × 10−7 M, and the RSD for 25 replicate determination of 2.00 × 10−5 M ferulic acid is 1.20%. This proposed method has the advantage of wide linear range, high selectivity and sensitivity. This proposed method was applied to the analysis of sodium ferulate injection with satisfactory results.