title: Electrochemical impedance spectroscopy versus cyclic voltammetry for the electroanalytical sensing of capsaicin utilising screen printed carbon nanotube electrodes.
abstract: Screen printed carbon nanotube electrodes (SPEs) are explored as electroanalytical sensing platforms for the detection of capsaicin in both synthetic capsaicin solutions and capsaicin extracted from chillies and chilli sauces utilising both cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). It is found that the technique which is most applicable to the electroanalytical detection of capsaicin depends upon the analyte concentration: for the case of low capsaicin concentrations, CV is a more appropriate method as capsaicin exhibits characteristic voltammetric waves of peak heights relevant to the capsaicin concentration; but for the case of high capsaicin concentrations where the voltammetric waves merge and migrate out of the potential window, EIS is shown to be a more appropriate technique, owing to the observed linear increases in R(ct) with increasing concentration. Furthermore, we explore different types of screen printed carbon nanotube electrodes, namely single- and multi- walled carbon nanotubes, finding that they are technique-specific: for the case of low capsaicin concentrations, single-walled carbon nanotube SPEs are preferable (SW-SPE); yet for the case of EIS at high capsaicin concentrations, multi-walled carbon nanotube SPEs (MW-SPE) are preferred, based upon analytical responses. The analytical performance of CV and EIS is applied to the sensing of capsaicin in grown chillies and chilli sauces and is critically compared to 'gold standard' HPLC analysis.
authors.affiliation: Faculty of Science and Engineering, School of Chemistry and the Environment, Division of Chemistry and Environmental Science, Manchester Metropolitan University, Chester Street, Manchester M1 5GD, Lancs, UK.
authors.forename: Edward P
authors.initials: EP
authors.lastname: Randviir
authors.forename: Jonathan P
authors.initials: JP
authors.lastname: Metters
authors.forename: John
authors.initials: J
authors.lastname: Stainton
authors.forename: Craig E
authors.initials: CE
authors.lastname: Banks
mesh_terms: D002211:Capsaicin / Q000032:analysis*; D055664:Electrochemical Techniques; D004566:Electrodes; D037742:Nanotubes, Carbon / Q000737:chemistry*
chemical_list: D037742:Nanotubes, Carbon; D002211:Capsaicin