ORTHOGONAL ARRAY DESIGN AS A CHEMOMETRIC METHOD FOR THE OPTIMIZATION OF ANALYTICAL PROCEDURES .1. 2-LEVEL DESIGN AND ITS APPLICATION IN MICROWAVE DISSOLUTION OF BIOLOGICAL SAMPLES

The theory and methodology of two-level orthogonal array design for th e optimization of analytical procedures were developed. In the theoret ical part, the matrix of the two-level orthogonal array design is desc ribed while orthogonality is proved by a linear regression model. Then , the assignment of experiments in a two-level orthogonal array design and the application of the triangular table associated with the corre sponding orthogonal array matrix are illustrated, followed by the data analysis strategy, in which significance of the different factor effe cts is quantitatively evaluated by the analysis of variance (ANOVA) te chnique and the percentage contribution method. Finally, a linear regr ession equation representing the response surface is established to es timate the factors that have a significant influence. In the applicati on section, microwave dissolution fog the determination of selenium in biological samples by hydride generation atomic absorption spectromet ry as a practical example is employed to demonstrate the application o f the proposed two-level orthogonal array design in analytical chemist ry.