Optimization of instrumental variables. Flow rates of
CL reagents were simultaneously studied in the range from 1
to 2 mL min−1 using the optimized reagent concentration values above mentioned by means of a 22 screening design plus
three centred points. Both factors were significant and were
subsequently optimized with a 22 central composite design
plus face centred star (with three centred points). The optimum values obtained from the response surface (Fig. 3(B))
were 2.00 and 1.54 mL min−1 for luminol and potassium permanganate solution flow rates, respectively.