| The compound 8-hydroxyquinoline-5-sulfonic acid (HQS) is added to the mobile phase as a complexing and ultraviolet detection reagent in metal ion chromatography. The optimum detection wavelength is 362 nanometers. The chromatography is complicated by formation of both neutral and anionic metal-HQS complexes for metals with large complexation constants, resulting in broad or multiple peaks using certain mobile phase formulations. The sample injection causes a peak by disturbing the adsorption equilibrium of HQS on the column. The effect of HQS and potassium nitrate concentration and flow rate on retention times and chromatographic efficiency is explored. Injection of more than one metal resulted in increased retention times, presumably due to competition for a fixed concentration of HQS in the mobile phase, and slower mass transfer out of the stationary phase. |
