Continuous and simultaneous determination of anions and cations in rainwater by ion chromatography

Abstract

A simple and sensitive method was investigated for the continuous and simultaneous determination of inorganic anions (SO₄²⁻, Cl⁻, NO₃⁻, F⁻) and cations (Na⁺, NH₄⁺, K⁺, Mg²⁺, Ca²⁺) in rainwater over a period of 18 h. A solution of 5 × 10⁻³ mol L⁻¹DL-malic acid–5% methanol–water was used as the eluent. Good simultaneous separation of anions and cations based on an ion-exclusion mechanism and a cation-exchange mechanism was achieved within 30 min with conductimetric detection. The method was successfully applied to rainwater detection, and proved to be a very useful method for real-time rainwater analysis.