Simultaneous Electroanalysis of Guaiacol and its Analogs Based on their Differential Complexation with α-Cyclodextrin on Nafion Modified Boron-doped Diamond Electrode

Guaiacol and its analogs, a distinct flavor in whiskey, foods, and beverages, display different inclusion complexes with α-Cyclodextrin (α-CD) and can be detected on a Nafion modified boron-doped diamond (BDD) electrode. The stable Nafion layer preconcentrates the analyte-α-CD complexes prior to electroanalysis by square wave voltammetry (SWV) to enhance detection sensitivities. This sensing mode together with peak deconvolution successfully distinguishes between guaiacol, 4-ethylguaiacol (4-EG), three cresol isomers, and phenols in a popular whiskey brand. The results obtained are corroborated by high-performance liquid chromatography (HPLC). Anodic oxidation at + 2 V in phosphate buffer, pH 7 is proven as an effective method to renew the electrode surface after its exposure to the guaiacols. This robust approach circumvents several drawbacks associated with the use of enzymes and nanomaterials for the analysis of such analytes as reported in the literature.