Off-line optimization of the separation of 2,4-dinitrophenylhydrazones by gas chromatography using chemometric techniques.

An off-line optimization technique based on soft modeling methods has been used to determine the optimum conditions for the separation of eight carbonyl-2,4-dinitrophenylhydrazones by gas chromatography equipped with a nitrogen-phosphorous detector. In this method theoretical simulations of peak retention time and peak width at base-line are coupled to a factorial design to map the chromatographic response surface. The calculated retention times from isothermal data have been used to calculate the chromatographic parameters. A full 3(3) factorial design was used to locate the optimum conditions for the temperature program, utilizing initial oven temperature, T(i), the programming rate for the first ramp, PR(1), and the programming rate for the second ramp, PR(2) as independent variables. The optimum conditions obtained for these parameters were: T(i), 140 degrees C; PR(1), 12 degrees Cmin(-1); PR(2), 8 degrees Cmin(-1). The maximum analysis times achieved by this optimum was 10.6 min.