Simultaneous ion-exclusion/cation-exchange chromatography of anions and cations in acid rain waters on a weakly acidic cation-exchange resin by elution with sulfosalicylic acid

A simple, selective, and sensitive method for the simultaneous determinatio n of anions (sulfate, nitrate, and chloride) and cations (sodium, ammonium, potassium, magnesium, and calcium) in acid rain waters was developed using ion-exclusion/cation-exchange chromatography with conductimetric detection . A weakly acidic cation-exchange resin column (Tosho TSKgel OA-PAK-A) and a sulfosalicylic acid-methanol-water eluent was used. With a mobile phase c omprising 1.25 mM sulfosalicylic acid in methanol-water (7.5:92.5) at 1.2 m l/min, simultaneous separation and detection of the above anions and cation s was achieved in about 30 min, Linear calibration plots of peak area versu s concentration were obtained over the concentration ranges 0-1.0 mM for an ions (R = 0.9991) and 0-0.5 mM for cations (R = 0.9994). Detection limits c alculated at S/N = 3 ranged from 4.1 to 14.8 ppb for the anions and from 2. 4 to 12.1 ppb for the cations. The reproducibility of retention times was 0 .14-0.15% relative standard deviation (RSD) for anions and 0.18-0.31% for c ations, and reproducibility of chromatographic peak areas was 1.22-1.75% RS D for anions and 1.81-2.10% for cations, The method was applied successfull y to the simultaneous determination of anions and cations in aerosols trans ported from mainland China to central Japan, as determined by a meteorologi cal satellite data analyzer. (C) 2000 Elsevier Science B.V. All rights rese rved.