ORTHOGONAL ARRAY DESIGNS FOR THE OPTIMIZATION OF LIQUID-CHROMATOGRAPHIC ANALYSIS OF PESTICIDES

Orthogonal array designs were applied to the optimization of liquid ch romatographic analysis of pesticides used in golf courses. Three varia bles related to the composition of the mobile phase were studied: the percentage of acetonitrile, percentage of methanol, and the buffer pH. In the first experiment, each variable was tested at three levels usi ng an OA(9) (3(4)) matrix, in which the interactions between the param eters were temporarily neglected. Based on the results of the first ex periment, the second experiment was carried out following a two-level orthogonal array design with an OA(8) (2(7)) matrix, in which more exa ct levels for each variable were chosen, and the interaction effects w ere considered separately. Finally, the optimum conditions for liquid chromatographic analysis of the pesticides were proposed. The advantag es and the disadvantages of three-level and two-level orthogonal array designs were discussed.