ABSTRACT
Positions of separated zones on thin-layer (and paper) chromatograms are described by the RF value of each substance, where
The point of greatest density is used for measurement of the location of the zone; for a symmetrical zone, that point is the center of the zone (see Figure 2.2). RF values range from 1.0 for zones migrating at the solvent front to 0.0 for a zone not leaving the point of application. Only two decimal places can be determined with validity. When RF data are tabulated, it is more convenient to report RF× 100 or hRF values. In conventional thinlayer chromatography, or especially for the techniques of overrun (continuous) or multiple development, where the solvent front is not measurable, Rx values can be recorded. Rx is defined by the equation
Unlike RF, Rx values can be greater than 1.
