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of the solutes with the stationary phase would become almost exclusively dispersive. This is an example where the phase system is complex and is required to be so, because limited column efficiency demanded clever phase selection to obtain the necessary differential retention. Analysis of b -blockers Another liquid chromatography application that involves some novel derivatization is the separation of some 'b blockers', the enantiomers of propranolol, metroprolol and atenalol as fluorescent enhanced derivatives on cellulose tris(3,5–dimethylphenylcarbamate) coated on silica gel. This technique was developed by Yang et al. [14] developed and involved the synthesis of their fluorescent derivatives, which were formed by reacting them with an electrophilic fluorogenic reagent, 4-(N-chloroformethyl-N- methylamino-7-N- N–dimethylaminosulfonyl-2, 1, 2–benzoxydiazole (DBD- COCl). These derivatives show intense fluorescence at

nbsp; Courtesy of the Royal Society of Chemistry, Ref. [14]   Figure 48 The Separation of Derivatized Propranolol (Pro) Metroprolol (Met) and Atenolol (Ate

nbsp; The detection limits at a signal-to-noise ratio of 3 were 50 fmol for both (S)- and (R)-Propanolol, 12 and 17 fmol for (S)- and (R)-Metroprolol respectively and 15 and 20 fm for (S)- and (R)-Atenolol respectively.   The cyclodextrin based stationary phases are some of the more popular and effective chiral stationary phases presently available. One of their distinct advantages lies in their unrestricted and successful use with all types of solvent. In particular, they can be used very effectively in the reversed phase mode (a method of development that is not possible with some other chiral stationary