A term which is equivalent to relative retention used in @C01182@: the ratio of the \(R_{\text{F}}\) value of a component to the \(R_{\text{F}}\) value of a standard (reference) substance. Since the mobile phase front is common for the two components, the \(R_{\text{F}}\) value can be expressed directly as the ratio of the distances travelled by the spot of the compound of interest (\(b_{i}\)) and the reference substance (\(b_{\text{st}}\)) respectively: \[R_{\text{rel}}=\frac{R_{\text{F}\left(i\right)}}{R_{\text{F}\left(\text{st}\right)}}=\frac{b_{i}}{b_{\text{st}}}\] In former nomenclatures the symbol \(R_{\text{s}}\) was used to express relative retardation in @P04682@. Because of its identity with the symbol for peak resolution the symbol \(R_{\text{rel}}\) is suggested for relative retardation in @P04682@.