Determination of inorganic cations and anions by ion-exchange chromatography with evaporative light-scattering detection

Evaporative light-scattering detection (ELSD) was investigated for the dire ct determination of alkali and alkaline-earth cations by cation-exchange ch romatography. Successful single run analysis of Na+, K+, Mg2+ and Ca2+ was achieved in 11 min on the Hamilton PRP-X200 column using an aqueous solutio n of ammonium formate as mobile phase under a salt concentration step gradi ent mode (20 mM and 100 mM). Surprisingly the use of ELSD reveals a weak re tention of inorganic anions (Cl-, NO3-, SO42-) onto the polymeric cation ex changer, which enables the simultaneous determination of inorganic anions ( Cl- and NO3-) associated with the cations analysed (Na+ and K+). (C) 2001 E lsevier Science B.V. All rights reserved.