Interpretative optimization of the isocratic ion chromatographic separation of anions

Abstract

Interpretive retention modeling was utilized to optimize the isocratic ion chromatographic (IC) separation of the nine anions (formate, fluoride, chloride, nitrite, bromide, nitrate, phosphate, sulfate and oxalate). The carbonate-bicarbonate eluent was used and separation was done on a Dionex AS14 ion-exchange column. The influence of combined effects of two mobile phase factors, the total eluent concentration (2-6 mM) and the carbonate/bicaronate ratio from 1:9 to 9:1 (which correspond to pH range 9.35-11.27), on the IC separation was studied. The multiple species analyte/eluent model that takes into account ion-exchange equilibria of the eluent and sample anions was used. In order to estimate the parameters in the model, a non-linear fitting of the retention data, obtained at two-factor three-level experimental design, was applied. To find the optimal conditions in the experimental design, the normalized resolution product as a chromatographic objective function was employed. This criterion includes both the individual peak resolution and the total analysis time. A good agreement between experimental and simulated chromatograms was obtained.

Ambient air particles: The use of ion chromatography and multivariate techniques in the analysis of water-soluble substances

“…17 The derivatization process is often troublesome, and it was shown that the application of IC for LMW organic acids analysis is more advantageous than GC-MS. 18 An optimized IC method can readily measure the major cations (sodium, ammonium, potassium, magnesium, calcium) and inorganic anions (chloride, nitrate, sulfate, oxalate, phosphate, bromide), even if they are present at a very low level in aqueous solution. [19][20][21] Here, an isocratic IC in the cation-exchange mode is applied for the analysis of five common cations, whereas twelve inorganic anions and LMW organic acids were simultaneously analyzed by an anion-exchange gradient IC.…”