Simultaneous ion-pair chromatography of inorganic anions and cations using on-column derivatization with chelating agents and UV detection

Six complexones have been investigated as on-column derivatizing agents for the simultaneous separation of inorganic anions and cations using ion pair chromatography. UV spectrophotometry at 210 nm has been applied for both the direct and the indirect detection of anions and anionic metal complexes. Under the experimental conditions used DCTA and DTPA have been practically applicable. Factors affecting the chromatographic behaviour of analyte ions have been studied. Chloride, nitrite, nitrate sulphate, chromate, molybdate, iron, chromium (III), copper (II), cobalt (II), nickel (II) and mercury (II) ions have been separated in 30 min with a mobile phase containing 1 mmol/1 TBA and 0.5 mmol/1 DCTA at pH 6.2 in acetonitrile-water (10:90 v/v). With DTPA as eluent and using pre-column derivatization of metal cations with DCTA eight anions and six metal cations can be separated. The detection limits are less than 0.1 mg/l for most of the investigated ions. Permanent address: Department of Analytical Chemistry, Vilnius University, Naugarduko 24, 2006 Vilnius, Lithuania