Abstract

CARRILLO-CEDILLO, E. G.; HARO-VAZQUEZ, M. P.; DIAZ TRUJILLO, G. C.  and  CANIZARES-MACIAS, M. P.. Plackett-Burman Factorial Design for the Optimization of a Spectrophotometric Flow Injection Method for Phenol Determination in Tap and Bottled Water Using 4-Aminoantipyrine. J. Mex. Chem. Soc [online]. 2014, vol.58, n.2, pp.99-105. ISSN 1870-249X.

Plackett-Burman and Quarter fraction 2^5-2 factorial designs were applied to evaluate a spectrophotometric flow injection method in order to determine phenol in water by using 4-aminoantipyrine (4-AAP) as derivatizing reagent. With a minimum number of experiments, the designs enabled the best conditions for phenol analysis: 80 cm and 180 cm reactors; flow-rates being: NH₃ 1.0 mL min^-1; 4-AAP 0.35 mL min^-1 and K₃[Fe(CN)₆] 0.35 mL min^-1, [NH₃] 0.064 mol L^-1, [4-AAP] 9.84 × 10^-3 mol L^-1, [K₃[Fe(CN)₆]] 0.02 mol L^-1, and an injection volume of 200 µL. With the optimized method it was possible to increase the lineal range from 0.3 µg mL^-1 to 30 µg mL^-1 and also to quantify the maximum allowable phenol concentration in water in comparison with other standard and flow injection methods whose lineal range are from 0.5 µg mL^-1 to 20 µg mL^-1 and from 0.5 µg mL^-1 to 16 µg mL^-1, respectively. The detection limit was of 0.13 µg mL^-1 and the regression coefficient was of 0.9999, making possible a throughput of 36 determinations an hour with a minimum consume of reagent. With the proposed method, a distillation step was not necessary to remove sulfates but, when the sulfate:phenol ratio was higher than 83, the analytical signal for phenol increased 8%, but hypochlorite interfered with the signal when the hypochlorite:phenol ratio was higher than 1.

Keywords : Plackett-Burman factorial design; phenol; 4-aminoantipyrine; water; flow injection; spectrophotometry.

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