[Study of the separation factors of basic compounds in HPLC using a reversed-phase amino-type column]

The chromatographic behaviors of some basic probes and a neutral reference compound were investigated as functions of temperature, buffer cation strength and flow-rate using a novel reversed-phase amino-type column at both pH 3.0 and pH 7.0. The results showed that the retention of basic compounds declined steeply at first, but then slowly when temperature increased continually at pH 3.0 while decreased slowly in the whole range of temperature at pH 7.0. The column efficiency increased and the peak shape improved with increased temperature. The buffer cation strength has a strong effect on the retention of bases. The optimum flow-rate for the highest efficiency is generally lower for basic compounds than neutral compounds, and due to the steepness of the van Deemter curves obtained, high flow-rates appear to be particularly detrimental in the chromatography of basic compounds. All the results indicated that the retention mechanism, was more complex for the analysis of bases on amino-type columns than on traditional reversed-phase columns because of the existence of amino group in the alkyl group of amino-type columns.