RESUMO
The sequential simplex strategy has been used to optimize the mobile phase used for separation of inorganic anions by micellar chromatography on a C(18)- micro Bondapak column, with absorption detection at 230 nm. The amount of acetonitrile and the concentration of phosphate buffer (pH 6.0) were chosen for optimization. The optimum mobile phase was found to be 38% acetonitrile in 18.2 mmol L(-1) phosphate buffer (pH 6.0) containing 10 mmol L(-1) cetyltrimethylammonium bromide (CTAB); this optimum was achieved within seven experiments. The separation of the five anions (nitrite, nitrate, iodide, thiocyanate, and thiosulfate) was accomplished in 18 min.
RESUMO
The sequential simplex algorithm was used to optimize the ion-pair reversed phase high performance liquid chromatographic (IP-RPHPLC) analysis of 4-(2-pyridylazo)resorcinol (PAR) chelates of Co(II), Ni(II) and Cr(III). A chromatographic response function (CRF) which included the number of peaks, the resolution between adjacent peaks, a specified analysis time, and the individual retention times relative to a minimum retention time, was calculated to evaluate the quality of the individual chromatograms. The optimum conditions for the three experimental parameters were 28.6% acetonitrile in the mobile phase, 3.0 mmol l(-1) concentration of acetate buffer at pH 6.0, and 5.2 mmol l(-1) tetrabutylammonium bromide (TBABr). Optimum conditions were achieved in only 19 experiments. The order of elution was Co(II)PAR, Cr(III)PAR and Ni(II)PAR, respectively, with an analysis time of 15 min.