In this application, 6 various mixed-mode phases were screened for separation of two neutral compounds. Experiments were conducted on four cation-exchange mixed-mode HPLC columns (Primesep P, Primesep 200, Primesep 100, and Primesep C) and two anion-exchange mixed-mode columns (Primesep D and Primesep B2). All phases showed different selectivity towards HPLC separation of prednisolone and glucose pentaacetate. Application shows that mixed-mode chromatography is a valuable tool in separation of neutral compounds by reversed-phase mechanism. Compounds were monitored by ELSD.

Effect of buffer concentration on retention and selectivity of HPLC separation of prednisolone and glucose pentaacetate was studied on a mixed-mode Primesep P cation-exchange column.

Prednisolone, atrolactic acid, and ibuprofen were separated in one HPLC run on an Obelisc R HPLC column. Obelisc R columns have C12 carbon chain and basic and acidic groups on the surface of silica gel. Compounds are separated by combination of reversed-phase, cation-exchange, and anion-exchange mechanisms. Obelisc R column can be used for retention and separation of acidic and basic hydrophilic compounds, acidic and basic hydrophobic compounds, and neutral compounds. Elution is monitored by common detection techniques like UV, ELSD, CAD and LC/MS.