Influence of metal impurities sorption onto a silica based C-18 stationary phase on the HPLC of metal chelating analytes

The chromatographic performance of metal chelating analytes on a C18 silica based stationary phase was studied. The influence of metal ions impurities on their peak shapes and the metal ions exchange properties of such a stationary phase were investigated. Evidence was obtained to support the proposition that sorption of metal ions onto the stationary phase base results in a chromatographic performance loss of the investigated metal chelating analytes. Since their retention is a function of strong complexing interactions and van-der-Waals forces, the mixed retention mechanism is best described as one of 'metal interaction'