Ethylenediamine as eluent component in cation chromatography. Predictive and comparative study for analysis of...

The retention behaviour of alkaline earth cations was studied as a function of changing composition of acidified ethylenediamine eluent. The multiple eluent species retention model developed for separation of calcium, magnesium and strontium ions was utilized for determination of selectivity coefficients for sample and eluent ions. The suggested model accurately describes and predicts retention of analytes under elution conditions [0.5-2.0 mM C2H4(NH2)2 and pH 4-6] which are of practical importance. The results in three-dimensional retention surface with species distribution graphs are demonstrated. Complexometric titrations and ion chromatography (IC) were compared for the analysis of calcium and magnesium ions. Statistical data indicated that there was no evidence for relative differences between the two methods. However, IC gives several advantages over volumetric method.