IDENTIFICATION IN PLANAR CHROMATOGRAPHY BY USE OF RETENTION DATA MEASURED USING CHARACTERIZED MOBILE PHASES

This paper defines three new technical terms for the characterization of mobile phases: the individual selectivity factor (S(f)), the total selectivity factor (S(F)) and the identification probability (I(P)). For the characterization of a single solvent S(f) is defined as a quotient of the proton acceptor (X(e)) and proton donor (X(d)) values of the Snyder solvent classification data. If a multicomponent (n component) mobile phase is used, the resultant S(F) is, by analogy with the total solvent strength, given by a sum of the individual selectivity factors of the components, weighted by multiplication with the volume fraction (phi). The identification probability is defined as the area of the triangle, formed by three mobile phases characterized by different values for total solvent strength (S(T)) and total selectivity factor (S(F)), where the hR(F) values of the unknown compounds are identical with those of the standard substances. The higher the value of I(P), the greater is the probability that sample and standard are identical. For routin laboratory work the I(P) value should be between 0.1 and 0.5. For identification of probably new, naturally occurring compounds the value of I(P) should be greater than 0.5.