Simultaneous optimization of the resolution and analysis time in micellar liquid chromatography of phenyl thiohydantoin amino acids using Derringer's desirability function.

The chemometrics approach was applied for simultaneous optimization of resolution and analysis time of nine phenyl thiohydantoin amino acids in micellar liquid chromatography. Derringer's desirability function, a multi-criteria decision making method, was tested for the evaluation of the two different chromatographic performance goals. The effect of five experimental parameters on a chromatographic response function formed using two sigmoidal desirability functions was investigated. The sigmoidal functions were used to transform the optimization criteria, resolution and analysis time, into the desirability values. The factors studied were the concentration of sodium dodecyl sulfate, alkyl chain length of the alcohol used as the organic modifier, organic modifier content, mobile phase pH and temperature. The experiments were performed according to a face-centred cube response surface experimental design to map the chromatographic response surface. Then, calculated chromatographic response functions were fitted to a polynomial model. The obtained regression model was characterized by both descriptive and predictive ability (R2 = 0.988 and R(2)cv = 0.973). The model was verified, as good agreement was observed between the predicted and experimental values of the chromatographic response function in the optimal condition. Based on the results of the study, combination of response surface mapping with Derringer's desirability function allows to predict the best operating condition in micellar liquid chromatography of phenyl thiohydantoin amino acids with respect to resolution and analysis time.