Optimized reverse-phase high-performance liquid chromatographic separation of cinnamic acids and related compounds.

The effect of mobile-phase pH on reverse-phase high-performance liquid chromatographicseparation is studied for a nine-component sample containing cinnamic, ferulic, hydrocinnamic, p-coumaric, caffeic, phenylacetic, vanillic, and β-phenylpyruvic acids and phenylethylamine. A systematic optimization strategy is utilized: Retention times of each component are measured for mobile phases buffered with citric acid at pH's of 3.0, 4.0, 5.0, and 6.0; a mathematical model is fit to the chromatographic data; the model parameters are used to construct a window diagram which provides an estimate of the mobile-phase pH required for optimum separation.