Peak parking technique for the simultaneous determination of anions and cations

An ion chromatography method is described for the simultaneous determination of anions (Cl-, NO3-, and SO4(2-)) and cations (Na+, NH4+, K+, Mg2+, and Ca2+) using a single pump, a single eluent and a single detector. An anion-exchange column modified with chondroitin sulfate C facilitated the elution of the above three anions using 5 mM tartaric acid as the eluent in isocratic mode, whereas the same eluent facilitated the separation of the above five cations on a commercially-available cation-exchange column. The separation columns were connected in series via two six-port switching valves, so the required cation-exchange or anion-exchange separation could be carried out by selecting the appropriate positions for the switching valves. The separations were completed in 30 min.