POTENTIOMETRIC DETERMINATION OF CHLORIDES WITH AN AIR-GAP CYANIDE SENSOR

A new electroanalytical method for determining chloride ions with an A ir-Gap cyanide sensor system is described. The method is based on the reaction of chloride with mercury(II) cyanide in dilute sulphuric acid . This reaction leads to hydrogen cyanide which can be determined with an Air-Gap cyanide sensor. Optimum concentrations of mercury(II) cyan ide and sulphuric acid were established and an analytical curve was pr epared for 1 x 10(-1)-1 x 10(-5)M Cl-. The slope of the calibration cu rve was equal to 62.8 mV/log C. The correlation coefficient (R) was eq ual to 0.9992. The method can determine chloride with good results in high saline solutions and in the presence of surfactants, which is in contrast to direct potentiometry with a chloride electrode. The method was applied for chloride determination in fuses used for initiating e xplosions. The chlorides were determined both in the raw materials use d to prepare the fuse braids and in the other fuse components. Chlorid e was also determined in drinking water and river water. In dependence of source, chloride amount analyzed in drinking water was in the rang e 2.18-182.6 mg/l. and 25.8 mg/l. in river water. A comparative analys is was carried out. In the first case, chloride was determined by a tu rbidimetric method, whereas in the second one by potentiometric titrat ion against a chloride-ISE.