OPTIMIZATION OF LIQUID-CHROMATOGRAPHIC PARAMETERS FOR THE SEPARATION OF PRIORITY PHENOLS BY USING MIXED-LEVEL ORTHOGONAL ARRAY DESIGN

Mixed-level orthogonal array design (OAD) as a chemometric method has been employed to optimize liquid chromatographic (LC) conditions far t he separation of environmental pollutants. Six parameters were examine d by OAD, namely reversed-phase (C-18) LC columns from different manuf acturers, content of methanol and acetonitrile in the mobile phase, in itial time-duration of a fixed mobile phase composition, time-duration of a gradient elution programme, and mobile phase flow rate. The opti mization of these parameters for the determination of eleven priority substituted phenols was carried out to demonstrate the applicability o f mixed-level OAD in environmental analytical chemistry in which the u se of trial-and-error procedures is often unsatisfactory due to sample complexity. The advantages and the disadvantages of mixed-level OAD w ere discussed.