Simultaneous optimization of the solid-phase extraction of organochlorine and organophosphorus pesticides using the desirability function.

In a multi-response situation [solid-phase extraction (SPE) of 18 organochlorine and nine organophosphorus pesticides from aqueous solution], several response variables are considered, and the optimization problem is more complex than in the single response case. Experimental design combined with desirability function was applied for the optimization of the SPE of these pesticides in order to obtain optimum operating conditions for routine work. This multi-criterion approach was developed for the simultaneous optimization of multiple responses and it is simple, easy to apply and permits the user to make subjective judgments on the importance of each response. The desirability function is based on the search for a global optimum [D = f (Y1, Y2, ..., Yn)] by the transformation of the measured property to a dimensionless scale for each criterion. The experimental design strategy involved a central composite design. A compromise between conflicting goals, such as achievement of good yields with SPE recoveries of ca. 100% for a large number of analytes with inherent chemical differences, was found by means of the desirability function D.