Iodide analysis by ion chromatography on a new stationary phase of polystyrene-divinylbenzene agglomerated with polymerized-epichlorohydrin-dimethylamine

A new stationary phase for iodide ion analysis has been developed. The cationic polymer-epichlorohydrin-dimethylamine (PEPI-DMA) was served as modifier in synthesizing polyelectrolyte sorbents and the macroporous polystyrene-divinylbenzene (PS-DVB) resin was used as support. The positively charged polymer (PEPI-DMA) was electrostatically bonded to a negatively charged particle (PS-DVB sulfonated). The new stationary phase was characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR), elemental analysis, chemical adsorption and desorption measurements. The chromatographic evaluation of the new stationary phase was performed using various anions with a conductivity detector. The new stationary phase was also applied to the determination of iodide directly with a DC amperometric detector using a platinum working electrode and an Ag/AgCl reference electrode. The chromatographic conditions were optimized and the eluent solution contained 5   mmol/L HNO 3 and 15   mmol/L NaNO 3 at a flow rate of 1.0   mL/min and column temperature of 30   °C. The applied voltage of the DC amperometric detector was 0.9   V. Under the optimum conditions, the linear range of the method was 0.2–50   mg/L for iodide ion with a correlation coefficient of 0.9990. The detection limit was 0.05   mg/L (calculated at S/N   =   3) and the relative standard deviations (RSD, n   =   6) were all less than 1% for retention time, peak area and peak height. This method was also utilized for the determination of iodide ions in samples of povidone iodine solution and kelp samples with satisfactory results.