I´ve been reading about peak tailing, loss of resolution and peak broadening in reversed phase columns and some authors explains that heavy metals can produce peak tailing on C18 columns. Any body knows why this happens?
Heavy metal impurities act as Lewis acids and produce strong interactions with the analytes e.g. you have an iron impurity (the most common one in silica), then iron ions (ferrous or ferric) held in the solid matrix can have strong interaction with a Lewis base such as an amine. Similarly carboxylate containing groups will also interact with metallic Lewis acids. Once you add another interaction in chromatography, your peak can potentially broaden. Just keep in mind that most of the metallic impurities come from the metal frits used in columns rather your mobile phase or samples over a period of time.
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