ORTHOGONAL ARRAY DESIGN AS A CHEMOMETRIC METHOD FOR THE OPTIMIZATION OF ANALYTICAL PROCEDURES .2. 4-LEVEL DESIGN AND ITS APPLICATION IN MICROWAVE DISSOLUTION OF BIOLOGICAL SAMPLES

The theory and methodology of a four-level orthogonal array design wer e developed for the optimization of analytical procedures. The constru ction and characteristics of an OA(16)(4(5)) matrix are described in d etail, and the orthogonality of the matrix is shown by means of a thir d-order regression model. The response surface methodology for the OA( 16)(4(5)) matrix was then developed by using the equations obtained fr om the proof of orthogonality. Microwave dissolution for the determina tion of selenium in biological samples by hydride generation atomic ab sorption spectrometry was used as a practical example to demonstrate t he application of the proposed four-level orthogonal array design with response surface methodology.