ION-SELECTIVE ELECTRODE POTENTIOMETRIC DETECTION IN ION-CHROMATOGRAPHY

Anion- and cation-responsive, all solid-state, tubular PVC membrane electrodes were used as detectors in nonsuppressed ion chromatography. Separation and detection of 11 monovalent inorganic and organic anions with a 2 muL cell volume detector were demonstrated using low concentration eluents. A simple and selective method for chromatographic separation and potentiometric detection at sub-ppb levels of seven cations was achieved in 7 minutes. As the detector was selective and sensitive only to monovalent cations, with no interference from other cations, the method was easily applicable to other sample types, including the determination of sodium and potassium ions in inorganic and organic chemicals. The overall efficiency of ion chromatographic procedures allows the possibility of routine separation and detection of inorganic and organic anions and cations at low levels in a simultaneous system. Thus, a simple, selective, sensitive, reproducible method was developed needing only 8 minutes or less to complete an independent separation and simultaneous potentiometric detection of 14 inorganic and organic monovalent common anions and cations with anion and cation-exchange columns in series. The method is flexible as the anions will not interfere with the detection of cations and cations will not interfere with the detection of anions, so that detectors can be used at the end of the two columns in series or one detector can be used at the end of each column. Applications to natural water samples are described.