Novel ECL Method for the Determination of Skatole in Porcine Adipose Tissue

Abstract

A new method for the determination of skatole present in porcine adipose tissue samples utilizing the electrochemiluminescence of skatole is presented. It has been observed that oxygen radicals produced at a high cathodic voltage can react with oxidized skatole to create an excited intermediate molecule that then relaxes, generating peak photon emission at around 480 nm. A strong electrochemiluminescence or electrogenerated chemiluminescence (ECL) signal using boron-doped diamond (BDD) electrodes was observed optimally when a reduction potential of −1.8 V was applied, held for 40 s, before holding an oxidation potential of 0.8 V for 10 s. Using this principle, a calibration curve using known concentrations of skatole showed good linearity (range 0.025–2 μM) and a very low detection limit (LOD, 0.7 nM). A method that demonstrates for the first time an approach that utilizes this ECL reaction, and has the potential to be developed into an analytical device for use in the slaughterhouse, has been developed. This was achieved by extracting skatole out of the porcine adipose tissues into acetonitrile - giving an extraction efficiency of 67.6%. This method was then validated by analyzing the skatole content of 33 pig fat samples that had been previously tested using a standard technique, high-performance liquid chromatography (HPLC), containing a range of concentrations (0.02–2.58 μg/g). This ECL method exhibited excellent reliability and correlation with HPLC, giving a R 2 coefficient of 0.911, thus demonstrating the potential for this method to be developed for an on-line skatole detector.

Highly Sensitive and Selective Detection of L-Tryptophan by ECL Using Boron-Doped Diamond Electrodes

“…In this case, hydroperoxy radicals are produced from dissolved oxygen and water. However, the reaction described by Okajima and co-workers has been observed to be completely inhibited in acetonitrile upon the addition of water, quenching for instance the chemiluminescence of 3-methylindole [ 48 ]. This is thus explained here by the absence of indole radical formation in the presence of water (proton donor).…”