Indirect UV Detection–Ion-exclusion/Cation-exchange Chromatography of Common Inorganic Ions with Sulfosalicylic Acid Eluent

Abstract

Herein, we describe indirect UV detection–ion-exclusion/cation-exchange chromatography (IEC/CEC) on a weakly acidic cation-exchange resin in the H⁺-form (TSKgel Super IC-A/C) using sulfosalicylic acid as the eluent. The goal of the study was to characterize the peaks detected by UV detector. The peak directions of analyte ions in UV at 315 nm were negative because the molar absorbance coefficients of analyte anions and cations were lower than that of the sulfosalicylic acid eluent. Good chromatographic resolution and high signal-to-noise ratios of analyte ions were obtained for the separations performed using 1.1 mM sulfosalicylic acid and 1.5 mM 18-crown-6 as the eluent. The relative standard deviations (RSDs) of the peak areas ranged from 0.6 to 4.9%. Lower detection limits of the analytes were achieved using indirect UV detection at 315 nm (0.23 – 0.98 μM) than those obtained with conductometric detection (CD) (0.61 – 2.1 μM) under the optimized elution conditions. The calibration curves were linear in the range from 0.01 to 1.0 mM except for Cl⁻, which was from 0.02 to 2.0 mM. The present method was successfully applied to determine common inorganic ions in a pond water sample.