Redox impulse, computational calculation of molecular energy potentials and ultra-trace determination of the food colorant erythrosine b in fruit jams, soft drinks and water

Abstract

The computational calculation of molecular energy potentials and redox behavior are of great importance in view point of prediction of food colorant characteristics such as energy levels, bandgaps of absorption and redox potentials values. Thus, the current study recognizes the electrochemical redox imprints of the underexplored food colorant erythrosine b (E127) in potential sources. The redox impulse and surface coverage (Γ) of the electro active E127 specie implied an explicit adsorptive differential pulse-cathodic stripping voltammetric (Ads-DP-CSV) tool for its trace analysis. Bridging the theoretical and experimental records, a standard sensing route was established to interpret the redox mechanism of E127 at the optimized pH (7.5) upon controlled electrochemical deposition followed by direct Ads-DP-CSV monitoring at −0.73 V on HMDE vs. Ag/AgCl electrode. The highest occupied molecular orbital energy (HOMO) (−4.90 to −4.92 eV) and the lowest unoccupied molecular orbital energy (LUMO) (−2.11 to −2.0 EV) distribution patterns in water and acetonitrile as computed using DFT/B3LYP/3–2G level and the corresponding band gap energy in water (2.8 eV) and acetonitrile (2.92 eV) gave evidence for the cut-off conjugation interaction between the benzoic part and other rings in the E127 molecule to assign the most probable electrochemical reduction mechanism. The negative charge is centered on the highest electronegative atom, oxygen (−0.17 to −0.30), and the positive charge on the iodine atoms (0.14–0.19). This practice was based upon controlled adsorptive deposition of E127 at pH 7.5 followed by direct Ads DP-CSV measurement of the reduced species at HMDE −0.79 V vs. Ag/AgCl electrode. The linear plot of the cathodic peak current (ip,c) at −0.73 V versus concentrations of E127 provided low limits of detection (LOD) and quantification (LOQ) of 0.18 and 0.594 µgL−1, respectively. The probe was robustly subjected to E127 analysis in jams, soft drinks, and water samples.