Voltammetric Determination of Anethole on La₂O₃/CPE and BDDE

In this work, DPV determination of anethole was presented using various carbon, two-diameter (1.5 and 3 mm) electrodes, that is, BDD, GC, CP, and CP doped by La₂O₃ and CeO₂ nanoparticles. La₂O₃/CPE to our best knowledge was proposed first time. Cyclic voltammograms confirmed totally irreversible electrode electrooxidation process, controlled by diffusion, in which two electrons take part. The most satisfactory sensitivity 0.885 ± 0.016 µA/mg L^-1 in 0.1 mol L^-1 acetate buffer was obtained for La₂O₃/CPE with the correlation coefficient r of 0.9993, while for BDDE it was 0.135 ± 0.003 µA/mg L^-1 with r of 0.9990. The lowest detection limit of 0.004 mg L^-1 was reached on La₂O₃/CPE (3 mm), what may be compared with the most sensitive conjugate methods, but in the proposed approach, no sample preparation and analyte separation was needed. Anethole was successfully determined in specially prepared ethanol extracts of herbal mixtures of various compositions, which imitated real products. The proposed procedure was verified in analysis of commercial products, that is, anise essential oil, which contains a large concentration of anethole, and in alcohol drinks like Metaxa, Ouzo, and Rakija, in which the considered analyte occurs on trace levels. Structure and properties of the considered nanopowders and graphite pastes were investigated by EDX, SEM, and EIS.