Investigation by experimental design and regression models of the effect of five experimental factors on ion-interaction high-performance liquid chromatographic retention

The effect on retention of simazine and atrazine of five experimental factors in ion-interaction chromatography is investigated by means of chemometrics. The factors are: (1) the chainlength of the ion-interaction reagent (N), (2) the concentration of the ion-interaction reagent (CR), (3) the pH of the mobile phase, (4) the flow rate (F) and (5) the organic modifier concentration (CM). Fractional and star experimental designs are employed. The effects of the factors and their interaction on retention are calculated and discussed: the results permit to draw out useful information concerning the interaction mechanisms involved. A regression model correlating the chromatographic retention to the factors, their second-order interactions and their squares with very good predictive ability (R2 > 97% and Rcv2 > 94%) is also calculated.