Electroanalytical Properties of Chlorophenol Red at Disposable Carbon Electrodes: Implications for Escherichia coli Detection

Charnete Casimero, Teri Bigham, Ruairi Mc Glynn, JSG Dooley, Nigel G Ternan, William J Snelling, Megan E Critchley, Cameron L Zinkel, Robert B Smith, Lyda P Sabogal-Paz, James Davis

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The use of coliforms and Escherichia coli as indicator species for assessing the quality of water is well established and a large variety of methods based on β-galactosidase (B-GAL) activity, inherent to the microbes within this classification, have arisen to enable their detection and enumeration. Chlorophenol red (CPR) is widely used as a chromogenic label, but its capacity for translation to electroanalytical devices has yet to be fully explored. The CPR moiety is capable of undergoing oxidation at carbon substrates (+0.7 V) giving rise to a variety of phenolic intermediates. Electrochemical, XPS and enzymatic techniques were employed to characterise the underpinning chemistry and the intermediate identified as a 1,2-quinone derivative in which the chlorine substituent is retained. The latter was found to accumulate at the electrode and, in contrast to the parent CPR, was found to be detected at a significantly less positive potential (+0.3 V). Bacterial hydrolysis of a CPR labelled substrate was demonstrated with the 1,2-quinone oxidation product found to accumulate at the electrode and detected using square wave voltammetry. Proof of concept for the efficacy of the alternative electrode pathway was established through the detection of E.coli after an incubation time of 2.5 h with no interference from the labelled substrates.

Original languageEnglish
Article number107321
Number of pages7
Early online date28 Jun 2019
Publication statusPublished (in print/issue) - 1 Dec 2019


  • Galactosidase
  • Chlorophenol red
  • Global Health
  • Water quality
  • Coliform


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