The deposltlon and stripping behavlor of sllver sulflde films at the silver rotatlng dlsk electrode were Investigated. The effect of various factors-rotatlon rate, scan rate, deposltlon potential and time, and concentration of sulflde Ion-on the stripplng peak current and potential were studled. The electrode has been found to be an excellent electrode for cathodlc strlpplng voltammetry for the determlnatlon of submicro amounts of sulfide Ion. Furthermore, dlfferentlal pulse voltammetry significantly enhanced the slgnal/nolse ratlo, and a linear response was obtalned over the concentration range 10-8-10-5 mol dm-' of sulfide Ion in 0.2 mol dm-3 NaOH.We describe a procedure for trace determination of sulfide ion in solution based upon the cathodic stripping of electrodeposited Ag& This procedure evolved from studies of the formation of silver sulfide upon anodization of a silver electrode in sulfide-containing solutions and properties of the electrodeposited silver sulfide films at silver rotating disk electrodes (RDE) (1, 2).Although anodic stripping voltammetry (ASV) is a wellestablished technique for the determination of trace levels of metal ions in solution, the equivalent method for the determination of anions by cathodic stripping voltammetry (CSV) is less established. Most of the reported applications of CSV for anions which form sparingly soluble compounds with the electrode have been carried out at hanging mercury drop or mercury pool electrodes. The determination of trace quantities of halide ( 3 4 , sulfide (6-11), cyanide (12), cyanoferrate(I1) and -(III) (13) and selenide ions (14,15), and various thiols (16-21) by deposition of their insoluble mercury salts has been reported. Several extensive reviews (22-24) covering stripping analysis have appeared and the reviews by Brainina have extensive sections on CSV.Trace amounts of iodide were determined by CSV by Shah and Perone (25) as early as 1961. Although they used a silver electrode, it appears that little work with this electrode for CSV has been performed since.The solution containing the analyte is usually vigorously stirred during deposition (ASV) or film formation (CSV) to increase the efficiency of the deposition step. The stripping (ASV) step is usually carried out from a quiescent solution since stirring perturbs the mercury drop or pool electrode (26). Since the rotating electrode hydrodynamics are very well defined, increasing use has been made of thin-film mercury electrodes on rotating glassy carbon substrates. However, there is a significant lack of literature on the use of an RDE for anion determinations employing CSV.This paper reports on the deposition and stripping of silver sulfide films at a silver RDE and describes a procedure for the determination of submicro levels of sulfide. Linear potential scan or differential pulse voltammetry is employed during the reduction step stripping the Ag2S from the electrode surface.EXPERIMENTAL SECTION Reagents. Analytical grade sodium sulfide (Na2S-9H20, Mallinckrodt Inc.) and sodium hydroxide ...