An article in Analytica Chimica Acta [Design-of- Experiment Optimization of Exhaled Breath Condensate Analysis Using a Miniature

An article in Analytica Chimica Acta [€œDesign-of- Experiment Optimization of Exhaled Breath Condensate Analysis Using a Miniature Differential Mobility Spectrometer (DMS)€ (2008, Vol. 628(2), pp. 155€“161)] examined four parameters that affect the sensitivity and detection of the analytical instruments used to measure clinical samples. They optimized the sensor function using exhaled breath condensate (EBC) samples spiked with acetone, a known clinical biomarker in breath. The following table shows the results for a single replicate of a 24 factorial experiment for one of the outputs, the average amplitude of acetone peak over three repetitions.

The factors and levels are shown in the following table. A RF voltage of the DMS sensor (1200 or 1400 V) B Nitrogen carrier gas flow rate (250 or 500 mL min€“1) C Solid phase microextraction (SPME) filter type (polyacrylate or PDMS€“DVB) D GC cooling profile (cryogenic and noncryogenic) 

(a) Estimate the factor effects and use a normal probability plot of the effects. Identify which effects appear to be large, and identify a model for the data from this experiment.

(b) Conduct an ANOVA based on the model identified in part (a). What are your conclusions?

(c) Analyze the residuals from this experiment. Are there any problems with model adequacy?

(d) Project the design in this problem into a 2r design for r < 4 in the important factors. Sketch the design and show the average and range of yields at each run. Does this sketch aid in data representation?

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Configuration 1 D 0.12 2 0.1193 3 0.1196 4 0.1192 0.1186 0.1188 0.1191 8. 0.1186 0.121 0.1195 10 11 0.1196 12 13 0.1191 0.1192 14 15 0.1194 0.1188 16 0.1188 +I + I +I + + + +I + + + I | + + 1 | + + | I + +| + + + + + + I | IIIII|