Factors other than the boiling points of compounds will also affect separation.
Other factors that determine the separation are: the polarity and physical size of the
molecules (for example branching), the column type (i.e. polar or nonpolar), and the
number of theoretical plates (Petrie). The polarity of compounds should be considered
because polar compounds will have a longer elution time on a polar column (i.e. the
stationary phase) while a nonpolar compound will elute in shorter times (Skoog 714).
The mobile phase flow rate (how fast the gas is carrying the compounds through) also
affects the appearance of peaks on the chromatogram (Skoog 683). If the flow is too fast,
peaks may not separate out as well, however, if the flow is too slow, band broadening
may occur. Column efficiency (comprised of plate height and the number of theoretical
plates) is another aspect that must be taken into account. The smaller the height
equivalent to a theoretical plate (the more theoretical plates present) the more efficient
the column