Highly stable voltammetric detection of nitroaromatic explosives in the presence of organic surfactants at a polyphenol-coated carbon electrode

A polyphenol-coated screen-printed carbon electrode is used for highly sensitive voltammetric measurements of the 2,4,6-trinitrotoluene (TNT) explosive in the presence of surface-active substances. The permselective/protective polyphenol coating offers excellent resistance to surfactant fouling, while allowing facile transport of the target TNT. High levels of gelatin, humic acid and sodium dodecyl sulfate (SDS) (up to 50 mg/L) have negligible effects upon the square-wave voltammetric TNT response. The TNT peak current and potential remain nearly the same in the presence of these organic macromolecules, as compared to substantial peak suppressions and shifts at the bare electrode. Control of the electropolymerization time was used for achieving the desired exclusion of interfering surface-active macromolecules while allowing transport of the target TNT. The response for ppm levels of TNT is highly linear and stable for prolonged operations in the presence of surface-active substances. By meeting the high sensitivity, selectivity, stability, portability and low-cost demands, such voltammetric sensing holds great promise for field-based voltammetric monitoring of nitroaromatic explosive compounds.