To quantify the separation between two compounds, another measure is provided by the resolution factor R. Contrary to the selectivity factor which does not take into account peak widths, the following expression is used to calculate R between two compounds 1 and 2 (Figure 1.9):
Other expressions derived from the preceding ones and established with a view to replacing one parameter by another or to accommodate simplifications may also be employed to express the resolution. Therefore expression 1.27 is used in this way.
It is also useful to relate the resolution to the efficiency, the retention factor and the separation factors of the two solutes (expression 1.28, obtained from 1.26 when w1=w2
). The chromatograms on Figure 1.10 present an experimental verification.