Critical Comparison of Paraffin Carbon Paste and Graphite-Poly(tetrafluorethylene) Composite Electrodes Concerning the Electroanalytical Behavior of Various Antioxidants of Different Hydrophobicity

Abstract

The voltammetric and flow-injection amperometric behaviors of several substances used as antioxidants in the food and pharmaceutical industries at carbon paste electrodes, with paraffin as binding agent, and at graphite-40 % PTFE composite electrodes were compared on the basis of the different hydrophobicity of the antioxidants. Aqueous solutions, alcohol-water mixtures and oil-in-water-emulsions were used as working media. No voltammetric or flow-injection responses were obtained for high hydrophobic antioxidants (BHT, Irganox-1076 and Irganox-1010) at graphite-PTFE electrodes. On the contrary, carbon paste electrodes allowed the attainment of analytically useful signals for these compounds. A pulse amperometric detection (PAD) scheme should be applied in these cases for the cleaning of the electrode surface. The use of graphite-PTFE electrodes seems to be advantageous for the less hydrophobic antioxidants such us propyl gallate and TBHQ. An adsorption process for PG and a faster electrode kinetic in the case of TBHQ were shown to occur by cyclic voltammetry at the PTFE composite electrode. Furthermore, this electrode allows the use of lower potentials for the amperometric detection of these compounds than the carbon paste electrode. Good reproducibility of the successive amperometric responses was also observed. The mutual influence of the electrode surface composition and the lipophilic characteristics of the molecules tested is discussed.

Electrochemical Sensing and Assessment of Parabens in Hydro- Alcoholic Solutions and Water Using a Boron-Doped Diamond Electrode

“…Having the longer alkyl chain, PB is a representative example of the more complex parabens from the explored series. The initiation of the anodic oxidation, corresponding to an anodic wave or current peak is a known characteristic of the de-electronation and dehydrogenation step in the oxidation pathways of the oxygen containing organics [17] and phenolic compounds [3, 9-13, 15-20]. …”

Long-Term Monitoring of Brain Dopamine Metabolism In Vivo with Carbon Paste Electrodes

“…In addition to the neurochemical studies cited below, applications of CPEs include environmental monitoring [68,69], drug analysis [70-72], determination of heavy metals [73] and toxins [74], biomedical monitoring [66,75-79], and food analysis [80,81]. …”

Composite amperometric tyrosinase biosensors for the determination of the additive propyl gallate in a reversed micellar medium

“…2 also shows an anodic current when a potential of +0.20 V was applied to the bioelectrode. This current is obviously not due to the reduction of the o-quinone but the electrochemical oxidation of PG at the graphite-Teflon composite electrode [24]. Taking into account that both background current and stabilization time of this background current increased as the applied potential was more negative, a potential value of −0.10 V was selected for subsequent studies.…”