Origin of system peaks in single-column ion chromatography of inorganic anions using high pH borate—gluconate buffers and conductivity detection

Single-column ion chromatography of inorganic anions with borate—gluconate buffers and conductivity detection produces system peaks as the result of complexation of polyvalent cations such as calcium. The complexes show retention due to ion-exchange and/or reversed-phase mechanisms. The system peaks can be avoided by treating the sample with a cation exchanger which replaces the polyvalent cations with sodium ions.