Electrochemical Detection of O,O-Diethyldithiophosphoric Acid at a Tosflex Film Modified Glassy Carbon Electrode

In this study, the electroanalytical application of Tosflex, a perfluoro-anion-exchange membrane which has not been studied as much as Nafion and poly(4-vinylpyridine), is demonstrated using diethyldithiophosphoric acid (DEDTP) as an example. DEDTP dimerizes upon electrochemical oxidation at a glassy carbon electrode (GCE), but the current corresponding to this oxidation is rather small for analytical purpose. A Tosflex polymer film modified glassy carbon electrode (TFGCE) was fabricated to improve the detection of DEDTP. In a pH 5.5 solution, DEDTP deprotonated to DEDTP− anion which was accumulated onto TFGCE by the anion-exchange feature of Tosflex followed by square-wave voltammetric determination. With 3 min accumulation, the analytical signal versus concentration dependence was linear from 2 ppb (1.07×10−8 M) to 400 ppb (2.16×10−6 M) with a regression coefficient of 0.995 and a detection limit of 0.4 ppb (2.1×10−9 M). Unlike many other anion-exchange polymer modified electrodes, the TFGCE showed excellent stability over the studied pH range of 1–9.