APPLICATION OF PVC-MEMBRANE IODIDE ION SELECTIVE ELECTRODE TO THE ANALYSIS OF SYSTEM CO-EXISTING OF BROMIDE AND IODIDE IONS

Preparation of PVC-membrane iodide ISE was described and its electrochemical behaviors,especially its use as an indicator electrode in the potentiometric titration of iodide or bromide in the presence of each other,were studied.Linear response of this electrode was found in the range of 4.0×10-5-1.0×10-2mol·L-1 of iodide ion,with Nernst response slope of 59 mV/pI.Life of this I--ISE was found to be more than a month.As shown by experimental results,bromide and iodide in a mixture were titrated satisfactorily in succession by using the PVC-I--ISE,but it was impossible by using a silver-ISE.Besides,the detection limit of the PVC-I--ISE was found to be 1.6×10-5mol·L-1 of iodide,which is much lower than that of Ag-ISE.