APPLICATION OF DOEHLERT DESIGNS IN THE OPTIMIZATION OF EXPERIMENTAL-VARIABLES ASSOCIATED WITH THE SIMULTANEOUS SOLVENT-EXTRACTION OF SEVERAL METALS

An experimental design (Doehlert matrix design) has been carried out i n this study to optimize the experimental variables for the simultaneo us solvent extraction of Fe, V, Mo and Sn in isobutyl methyl ketone-tr ibutyl phosphate with 5,5'-methylenedisalicylohydroxamic acid. Four va riables were examined: pH and perchlorate, chelating reagent and syner gistic agent concentrations. Two designs of tao factors were performed , giving two response surfaces, one for each two factors. The plots of the analytical signal versus the experimental variables selected give two response surfaces which allow the optimum conditions to be identi fied for the quantitative extraction of the four metal ions. This opti mization strategy is simple and quick, compared with the traditional u nivariate methodology.