C. Reis et al., APPLICATION OF THE SPLIT-PLOT EXPERIMENTAL-DESIGN FOR THE OPTIMIZATION OF A CATALYTIC PROCEDURE FOR THE DETERMINATION OF CR(VI), Analytica chimica acta, 369(3), 1998, pp. 269-279
A kinetic catalytic procedure for the determination of Cr(VI), based o
n the o-dianisidine oxidation reaction with hydrogen peroxide in a wea
kly acid medium was optimized with respect to both reactants [HCl, o-d
ianisidine and H2O2] and solvent composition [mixtures of water, aceto
ne and N, N-dimethylformamide], in order to achieve higher sensitiviti
es. This was accomplished by making use of a split-plot experimental d
esign which permitted simultaneous variations in both mixture and proc
ess variables, using a response surface approach. Ten mixture experime
nts were randomized at each one of the 23 factorial levels and error a
nalysis was performed using a split-plot approach. The optimal mixture
[water-acetone 70-30% m/m] and process variables [HCl: 6.0 x 10(-4) m
ol/l, o-dianisidine: 1.9 x 10(-2) mol/l and H2O2: 0.79 mol/l] values r
esulted in a significant sensitivity increase compared with a similar
procedure described in the literature. (C) 1998 Elsevier Science B.V.
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