EFFECT OF CO-MODIFIERS IN CYCLODEXTRIN-MODIFIED MOBILE PHASES ON THE REVERSED-PHASE HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC SEPARATION OF POLYAROMATIC HYDROCARBONS

The effect of two co-modifier containing tert.-butyl moieties, tert.-b utyl (N-hydroxy) carbamate and tert.-butyl carbazate, on the retention behavior of six polyaromatic hydrocarbons (PAHs) using cyclodextrin-m odified mobile phases has been examined. Both modifiers resulted in sh orter retention times for all PAHs, when a size-compatible cyclodextri n was present in the eluent. This decrease has been attributed to the formation of a ternary PAH-cyclodextrin-modifier complex. The apparent formation constants calculated for these complexes are of the order o f approximately 10(2) M(-1), with the exception of the beta-CD-pyrene complex, which was determined to have a 2:1 stoichiometry. Mixtures of beta- and gamma-cyclodextrins were used in the mobile phase along wit h tert.-butyl carbazate to achieve a baseline separation of all six PA Hs under 50 min.