B. Bourguignon et al., OPTIMIZATION IN IRREGULARLY SHAPED REGIONS - PH AND SOLVENT STRENGTH IN REVERSED-PHASE HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY SEPARATIONS, Analytical chemistry, 66(6), 1994, pp. 893-904
The feasible region in which experimental optimization can be carried
out is often irregular in shape, so that the performance of the usual
symmetric experimental designs is disappointing. This is illustrated b
y the optimization of pH and solvent strength in HPLC. The definition
of the feasible region is described. This region is searched with a se
t of uniformly spaced informative experiments determined with the Kenn
ard and Stone algorithm, The optimization procedure is sequential, and
the quality of each separation is judged by means of a multicriteria
decision-making method. if none of the experiments leads to a chromato
gram with an acceptable combination of optimization goals, then better
experimental conditions are searched by following chromatographic exp
ertise. The possibility of using D-optimal designs to model the chroma
tographic parameters over the feasible region is also discussed. As an
example, pH and solvent strength of the mobile phase are optimized in
the reversed-phase liquid chromatography separation of a mixture of f
our chlorophenols.