Determination of iodide in concentrated chloride springs by reversed-phase high-performance liquid chromatography with ultraviolet detection.

We developed a convenient and simple reversed-phase high-performance liquid chromatographic (RP-HPLC) method for analysis of iodide in concentrated chloride springs. Using a C18 column, the iodide and chloride peaks were well separated. Setting the wavelength at 240 nm allows direct ultraviolet (UV) detection of iodide without any UV or Schlieren effect due to the high chloride concentration. The high ionic strength of spring samples containing high levels of sodium chloride broadens the iodide peak. Iodide was quantified based on the peak areas of standard solutions of iodide, in which 100 mM sodium chloride was added to match the saline matrixes with the samples. The detection limit of iodide at a signal-to-noise ratio of 3 was 0.0003 mM. The detector response was linear over the concentration ranges of 0.001-0.1 mM. The proposed RP-HPLC/UV method was successfully applied to determine iodide in some concentrated chloride spring samples.