6.36 A paper in the Journal of Chemical Technology and Biotechnology ("Response Surface Optimization of the Critical Media
Components for the Production of Surfactin," 1997, Vol. 68, pp. 263-270) describes the use of a designed experiment to maximize
surfactin production. A portion of the data from this experiment is shown in Table P6.10. Surfactin was assayed by an indirect method
which involves measurement of surface tensions of the diluted broth samples. Relative surfactin concentrations were determined by
serially diluting the broth until the critical micelle concentration (CMC) was reached. The dilution at which the surface tension starts
rising abruptly was denoted by CMC-¹ and was considered proportional to the amount of surfactant present in the original sample.
a. Analyze the data from this experiment. Identify the significant factors and interactions.
b. Analyze the residuals from this experiment. Are there any indications of model inadequacy or violations of the assumptions?
c. What conditions would optimize the surfactin production?
6.37 Continuation of Problem 6.36. The experiment in Problem 6.36 actually included six center points. The responses at these
conditions were 35, 35, 35, 36, 36, and 34. Is there any indication of curvature in the response function? Are additional experiments
necessary? What would you recommend doing now?
Continuation:
Generate a response surface using 2 of the significant factors and their interactions (your choice of which
two), while keeping all other factors constant.
Describe a possible blocking scheme for Prob. 6.35 assuming 2 blocks are involved. You do not need to run
the analysis with blocks, just list which experiments would go in which blocks and why.
Note: do not simply print computer output. You must provide comments on your strategy as well as interpret
the results in a robust way.
Please answer all parts to above scenario. A, B, C, 6.37 continuation questions, and the further
continuation part below the first one.
Fig: 1