Sulfide sensing via differential counter ion diffusion rates through redox-modulated poly(vinylferrocene) microparticles

The use of poly(vinylferrocene) as an electrochemical sensor to measure sulfide has been previously demonstrated [K.L. Robinson, N.S. Lawrence, Electroanalysis, Advanced Article (2006)]. For long term monitoring it is essential that the voltammetric response is stable. This report details the experiments conducted to examine the stability of the poly(vinylferrocene) voltammetric response, which is shown to be critically dependent on the nature of the electrolyte solution and the voltammetric sweep rate (within the experimental timescale). At faster scan rates (0.5–1 V s−1) the response is anion insensitive with a slight decay in the signal observed for all anions studied. In contrast, at slower scan rates (0.01 V s−1), the voltammetric signals are highly dependent on the anion; where the smaller the anion, the more enhanced the response. The former conditions are demonstrated to enable an augmented sensitivity to the monitoring of sulfide.