The transport of catechols through perfluorinated cation-exchange films on electrodes

Abstract

Steady-state amperometric and chronocoulometrlc experiments were carried out with a glassy carbon rotating disk electrode coated with a film of the perfluorinated Ion-exchange polymer Nafion, In order to investigate the transport of anionic, cationic, and neutral catechols through the film. The distribution constants of the compounds between film and solution (Kd) were measured, and the diffusion coefficients In the film (Df) were calculated. The film diffusion coefficients of catecholamines were found to be In the range (0.5 to 3.0) X 10'7 cm2 s_1. The selectivity constants were determined of the Nafion film for catecholamines relative to three monovalent cations Ll+, Na+, and K+. The competitive effects of. the buffer cations were found to decrease In the order expected from literature data on the Ion-exchange selectivity of Nafion. The buffer cation concentration has no Influence on the transport of neutral catechols through the film, and for anionic catechols the effect was opposite to that for cations. Other important factors for the detection In flow-through systems were also investigated, such as the influence of the film thickness, the pH, and the methanol concentration. From the results guidelines were formulated to obtain maximum selectivity for cationic analytes with Nafion-coated electrodes in liquid chromatography and flow-injection analysis.

Tris(2,2′‐bipyridyl)ruthenium(II) Electrogenerated Chemiluminescence Sensor Based on Sol–Gel‐Derived V2O5/Nafion Composite Films

“…The ECL response decreased less than 10% over 5 h of operation period. In contrast, pure Nafionbased ECL sensor is rapidly destroyed upon exposure to mobile phases containing such high organic content as previously reported [36] so that the ECL response decreased 50% in 1 h operation. Thus, the present ECL sensor can be further used as a detector for reverse-phase high-performance liquid chromatography.…”

The use of chemically modified electrodes for liquid chromatography and flow‐injection analysis

“…Detailed studies of catechols transporting through Nafion on GCEs were recently given by Kok et al [69]. The film diffusion coefficients of catecholamines were found to be in the range of 0.5-3.0 X lo-' cm2/s.…”

Surfactant modified carbon paste electrode: Part 1: Electrochemical and microscopic characterization

“…Na' . or K4) was varied by 454 Digua et al adding the appropriate nitrate salts (2 M stock solution) [19]. Experiments were made using a 0.7 pM promethazine solution and 5 minutes accumulation.…”