MALDI 2^4+1 Factorial Example

We use data from a currently on-going factorial design experiment involving the matrix-assisted laser desorption/ionization (MALDI) time-of-flight mass spectrometry (TOFMS) analysis of synthetic polymer mixtures. While many variables are in a MALDI experiment are critical, only the quantity of the four different analyte polymers in a quaternary mixture are used in a 2^4+1 factorial design- other variables, including the quantity of matrix (as matrix-to-analyte ratio), quantity of cationization reagent (NaTFA), laser power, instrument settings, etc. are all held constant.

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Fractional Factorials and Confounding

We explore the reasons for use of a fractional factorial, then see how to set up a 1/2 fraction 2^3 factorial using the Excel spreadsheets we've already used. The idea of "confounding of variables" is also covered- with an explanation of how to ideally set up the fractional factorial to minimize confounding of the main effects.

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