Separation of Model Compounds in Reversed-Phase and Cation-Exchange Modes on Coresep 100 Mixed-Mode Column
Application description

Many pharmaceutical and chemical companies need a general approach for analysis of pharmaceutical ingredients and precursors. Developing universal screening procedures in chromatography can help save time in method development and utilize universal platform to analyze complex pharmaceutical mixtures,  formulation, metabolites, vitamins, etc. With over 600 reversed-phase column and thousands of mobile phase combinations chemists are facing a challenging task on what column to choose. In a lot of cases scientists need to develop several screening methods to address a complex mixture. Mixed-mode approach which combines reversed-phase, HILIC and ion-exchange mechanisms can address an issue of complex mixtures screening. When multiple columns are screened, very often in different modes of separation, multiple mobile phase needs to be prepared.  A simple and universal platform based on mixed-mode columns can be developed. This approach eliminates cumbersome multi-column multi-mobile phase efforts and streamlines method development process. Since mixed-mode columns explore at least two mechanism of interaction selectivity of the separation is drastically different. The model is based on the fact that compounds are retained by combination of reversed-phase and ion-exchange mechanism and that none of the compounds have exactly the same reversed-phase and ion-exchange properties. By exploring small difference in reversed-phase and ion-exchange properties, complex mixtures can be analyzed. The synergy effect of two mechanism allows longer retention and better selectivity than in traditional “single” mode approach. Short method with high efficiency was developed utilizing new core-shell mixed-mode column. All 7 compounds were separated within 5 minutes. Method and Coresep 100 column can be adopted in walk in labs for fast screening of new drug candidates and impurities, components of formulations and building blocks in chemical manufacturing. All methods are compatible with LC/MS and prep chromatography.

Conditions of Experiment
Column: Coresep 100
Separation Modes: reversed-phase and cation-exchange
Column Dimenstions: 3.2 x 100 mm, 2.7 um, 90A
Mobile Phase: ACN gradient from 10% to 65% in 5 min, buffer gradinet - Amonium formate pH 2.9 from 30 to 70 mM in 5 min
Detection: UV 270 nm, ELSD
Sample: 0.3 mg/ml
Injection: 1 uL
Flow rate: 1.2 ml/min
Class of compounds: Amines, Aromatic base, Aromatic compound, Isomer, Nucleoside
Nature of compounds: Basic, Hydrophilic, Polar
Compounds: Adenosine, 3,4-Difluoroaniline, 4-Amino-2-chloropyridine, 5-Aminoindole, 4-amino-3-chloropyridine, 2-Amino-5-methylthiazole, 4-Ethylaniline