An article in the Journal of Chromatography A ("Simultaneous Supercritical Fluid Derivatization and Extraction of Formaldehyde by the Hantzsch Reaction," 2000, Vol. 896, pp. 51-59) describes an experiment where the Hantzsch reaction is used to produce the chemical derivatization of formaldehyde in a supercritical medium. Pressure, temperature, and other parameters such as static and dynamic extraction time must be optimized to increase the yield of this kinetically controlled reaction. A 25-1 fractional factorial design with one center run was used to study the significant parameters affecting the supercritical process in terms of resolution and sensitivity. Ultraviolet-visible spectrophotometry was used as the detection technique. The experimental design and the responses are shown in Table P8.7.
(a) Analyze the data from this experiment and draw conclusions.
(b) Analyze the residuals. Are there any concerns about model adequacy or violations of assumptions?
(c) Does the single center point cause any concerns about curvature or the possible need for second-order terms?
(d) Do you think that running one center point was a good choice in this design?