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

The chromatographic performance of metal chelating analytes on a C-18 silic a based stationary phase was studied. The influence of metal ions impuritie s on their peak shapes and the metal ions exchange properties of such a sta tionary phase were investigated. Evidence was obtained to support the propo sition that sorption of metal ions onto the stationary phase base results i n a chromatographic performance loss of the investigated metal chelating an alytes. Since their retention is a function of strong complexing interactio ns and van-der-Waals forces, the mixed retention mechanism is best describe d as one of "metal interaction".