4 ethylphenol

4-ethylphenol (≥97.0%) and CeCl₃·7H₂O (≥99.0%) were purchased from Alfa Aesar (Karlsruhe, Germany). 1,4-phenylenediamine (≥99.0%) and Ce(OOCCH₃)₃·5H₂O (≥99.9%) were purchased from Sigma-Aldrich (Darmstadt, Germany). Ce(NO₃)₃·6H₂O was purchased from Honeywell Fluka (Seelze, Germany). Paraformaldehyde (≥95.0%) and absolute ethanol (≥99.5%) were purchased from VWR (Leuven, Belgium). The starting reagents were used without further purification.

Reagents used were analytical reagent grade chemicals, and all solutions were prepared using Milli-Q water (18.2 MΩ/cm; Millipore, Bedford, MA, USA). 4-Ethylguaicol was purchased from Alfa Aesar (98%; Haverhill, MA, USA); 0.1 M phosphate (KH₂PO₄) buffer solutions (Fluka, Munich, Germany) containing 0.1 M potassium chloride (Merck, Darmstadt, Germany) were used as supporting electrolyte for the electrochemical measurements; 1 M phosphoric acid (85%; Panreac, Barcelona, Spain) was used to adjust the pH of the buffer solutions to the adequate value; C₆₀ solutions (99.9%; Acros Organics, Geel, Belgium), used in the C₆₀/SPCE generation, were prepared using dichloromethane, purchased from Panreac (Barcelona, Spain), as solvent; 1.0 M KOH solutions (Carlo Erba, Val de Reuil, France) were used in the reduction of these modified electrodes; and 4-ethylphenol (97%; Alfa Aesar, Haverhill, MA, USA), 4-vinylphenol (10 wt% solution in propylene glycol; SAFC, St. Louis, MO, USA) and p-coumaric acid (> 98%; Sigma-Aldrich, Steinheim, Germany) were analysed as possible interferences.