COUNTERIONIC DETECTION BY ICP-AES FOR DETERMINATION OF INORGANIC ANIONS IN WATER ELUTION ION CHROMATOGRAPHY USING A ZWITTERIONIC STATIONARY-PHASE

The analytical methods for the determination of inorganic anions by wa ter elution ion chromatography using a zwitterionic column (C14SB-coat ed column) have been explored, where pure water was used as the mobile phase, In the present ion chromatography, the complicated peaks deriv ed from various ''ion pairs'' appeared on the chromatogram when the sa mple solution contained several kinds of cations and anions. The chrom atograms with the complicated peaks were simplified by using a precond itioning cation-exchange column. In the preconditioning column, variou s kinds of countercations of the analyte anions were converted to a pa rticular bind of common cation, and thus all the analyte anions were s eparated as the common cation form. The more effective separation was achieved by converting to a divalent cation (Mg2+) form than a monoval ent cation (Na+) form, because the anions paired with the divalent cat ion provided longer elution times than those paired with the monovalen t cation. All the analyte anions separated as the common cation form w ere simply determined from their calibration curves drawn from conduct ivity detection. In addition, the counterionic determination of the an ions was also attempted by using ICP-AES. The analyte anions mere dete rmined by measuring their countercations with ICP-AES, where the calib ration curve of the countercation measured blv ICP-AES could be used.