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Critical Comparison of Paraffin Carbon Paste and Graphite‐Poly(tetrafluorethylene) Composite Electrodes Concerning the Electroanalytical Behavior of Various Antioxidants of Different Hydrophobicity
Author(s) -
Diego Emilia,
Agüí Lourdes,
GonzálezCortés Araceli,
YáñezSedeño Paloma,
Pingarrón José M.,
Kauffmann JeanMichel
Publication year - 1998
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/(sici)1521-4109(199801)10:1<33::aid-elan33>3.0.co;2-w
Subject(s) - amperometry , electrode , graphite , cyclic voltammetry , carbon paste electrode , voltammetry , chemical engineering , carbon fibers , materials science , composite number , chemistry , chromatography , composite material , electrochemistry , engineering
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.