4-LEVEL ORTHOGONAL ARRAY DESIGN AS A CHEMOMETRIC APPROACH TO THE OPTIMIZATION OF POLAROGRAPHIC REACTION SYSTEM FOR PHOSPHORUS DETERMINATION

It is the purpose of the present work to provide information on the fo ur-level orthogonal array design and data analysis for the optimizatio n of analytical procedures. In the theoretical part, the construction and characteristics of the OA(16)(4(5)) matrix is described in detail, followed by the data analysis strategy, in which the significance of the different factors is quantitatively evaluated by an analysis of va riance (anova) method including per cent contribution, and the differe nce among four levels for each factor is determined by Duncan's multip le F test. Furthermore, a third-order polynomial model representing re sponse surface is established to estimate the effects for the factors with significant influences. In the application part, the proposed fou r-level orthogonal array design and data analysis method were applied to optimize polarographic reaction system for phosphorus determination . by conducting 16 preplanned experiments that span the maximum workin g range of the system, the best experimental conditions for achieving the largest response can be obtained. The expected value for each expe rimental trial calculated by the third-order regression equation estab lished is in good agreement with the corresponding experimental value. To confirm the validity of the optimization procedure, additional exp eriments using the recommended conditions were performed. The results demonstrate that satisfactory results can be acquired. Therefore, the proposed four-level orthogonal array design as a chemometric approach to optimize the polarographic reaction system for phosphorus determina tion is rater efficient and effective.