A protocol to replace dedication to either normal phase or polar organic mode for chiral stationary phases containing amylose tris(3,5-dimethylphenylcarbamate)

Abstract

Alteration of the enantiorecognition ability of polysaccharide-based chiral columns in the shipping normal phase (NP) eluent after exposition to polar organic (PO) mode eluents can be conceived as an incomplete hysteresis cycle. Non-standard solvents provide a solution to overcome this issue with immobilized stationary phases, but a procedure was missing so far to regenerate coated stationary phases from the altered state. Recent results with alcohol mixtures within the PO mode showed that an appropriate order of standard solvents may also be suitable to complete hysteresis. Using an analogous approach, a simple protocol was established to regenerate the original NP retentions on various stationary phases containing amylose tris(3,5-dimethylphenylcarbamate) (ADMPC) chiral selector after the change induced by flushing with 2-propanol or ethanol. The members of a chemically diverse compound set indicated that alterations in retentions and selectivities using different brands and types of ADMPC-based stationary phases can be quite different, but the recovery of the original state was very good for all of them. The proposed protocol eliminates the need of the costly dedication of a chiral column with ADMPC selector to either NP or PO mode. Furthermore, the limits of the alcohol content in the mobile phase compositions where the system is free of hysteresis were determined.