Abstract
A simple differential electrolytic potentiometry (DEP) is coupled with the flow injection analysis (FIA) for the total cyanide determination. This simple and rapid method is based on the reaction of a silver nitrate with cyanide to form silver cyanide complex. Potassium nitrate was used as a supporting electrolyte. Platinum, gold and silver electrodes were tested and among them silver amalgam was found to be a suitable indicating system. The optimum current density for polarizing the electrodes was found to be 10-17 μA / cm2. The sensitivity of the proposed method was further enhanced by shortening the coil length. The effect of flow rate and the volume of reagents and sample on the sensitivity of the method were also studied. The interference of chloride, iodide, sulfate, carbonate, phosphate, chromium, cobalt, nickel and cadmium were studied. Linear working range is from 1 ppm to 60 ppm. The detection limit is 0.5 ppm with a sample through put of 10 samples / hour and the correlation coefficient is 0.999. The equation for potential measurement was: [Potential (V) = 0.241 + 0.0091 x C (ppm)]. The described FIA-DEP has the additional advantages, over the other methods, of minimizing time and amount of consumed reagents and improving the accuracy of the analysis due to computer control.
