Chemometric analysis of highly overlapping voltammetric signals of chiral electrochemical sensor based on a nanocomposite of aspartame

Chiral discrimination received attention not only as an interdisciplinary subject in science, but also as a safety issue in medical, pharmaceutical and food industries [1]. An electrochemical chiral sensor was designed based on graphene (GR) as a catalyst for signal enhancement. Aspartame (ASP), an artificial non-saccharide sweetener, has been immobilized as a chiral selector on GR to discriminate electrochemical signals of mandelic acid (MA) enantiomers. A two-step electrodeposition strategy was used to fabricate ASP-loaded overoxidized polypyrrole film (ASP-OPPy) on GR-modified glassy carbon electrode, which was successfully utilized as working electrode for electrochemical enantioselective recognition of MA enantiomers based on an inhibitory sensing mechanism. The modified surface properties and the recognition mechanism were investigated using electrochemical analysis and DFT calculations. Under optimal conditions, the chiral sensor exhibited a good linear relationship with MA enantiomers concentrations ranging from 1–25 mM with a detection limit of 0.25 mM. Due to the highly overlapping signals, partial least squares (PLS) regression was applied to distinguish the MA enantiomers in their mixtures. In addition, the genetic algorithm-based potential selection procedure used to optimize the number of PLS factors used in building the PLS calibration models and its predictive ability was also studied.