Determination of sulfide at screen-printed electrode modified with ferricyanide-doped partially quaternized poly (4-vinylpyridine)

The indirect voltammetric method for determination of sulfide using the screen-printed electrode modified with ferricyanide-doped partially quaternized poly (4-vinylpyridine) in pH 7 phosphate buffer solution is reported. The electrode is prepared by adsorbing ferricyanide onto the screen-printed electrode coated with partially quaternized poly (4-vinylpyridine) anion-exchange polymer and finally sealing with sol-gel. The modified screen-printed electrode showed a highly stable and sensitive for sulfide analysis. The indirect electrochemical oxidation signal of sulfide appears at 0.2 V versus Ag/AgCl in pH 7 phosphate buffer solution. The calibration curve showed good linearity with a slope of 23.7 nA/mu M at 0.4-100 mu M sulfide. The detection limit (S/N = 3) was 0.12 mu M. This method was applied to the determination of sulfide in cigarette smoke sample.