Separation of purines and pyrimidines by normal-phase high-performance liquid chromatography using dimethyl sulfoxide in binary and ternary eluents

Analysis of purines and pyrimidines by mixed partition-adsorption normal-phase high-performance liquid chromatography

This paper summarizes the results in the development of mixed partition-adsorption (MPA) normal-phase high-performance liquid chromatography published in the last 10 years. The MPA normal-phase systems are an alternative approach not only to the adsorption normal-phase mode but also to the most widely used reversed-phase mode in the separation area of purine and pyrimidine derivatives. It is shown that the MPA systems are applicable in analytical practice.

Application of mixed partition-adsorption systems in high-performance liquid chromatography of purines and pyrimidines

Separation of the test mixtures of some purine and pyrimidine derivatives on silicas (types A and B) in adsorption normal-phase (A-NP) and mixed partition-adsorption normal-phase (MPA-NP) mode has been studied. When the A-NP mode is used the peak shapes are unsatisfactory (especially on type A silica). At the same time MPA-NP systems show a good peak symmetry on all silica types. The findings have demonstrated that the MPA-NP mode offers a specific selectivity. This allows MPA-NP systems to supersede reversed-phase systems in some application areas.

Normal-phase high-performance liquid chromatographic separations using ethoxynonafluorobutane as hexane alternative. I. Analytical and chiral applications

A novel, environmentally friendly, fluorinated solvent--ethoxynonafluorobutane--has been used to replace n-hexane in normal-phase HPLC applications. Fast gradients of methanol in ethoxynonafluorobutane on a cyano column have been successfully applied to the separation of steroids, benzodiazepines, NSAIDs, tricyclic antidepressants, beta-adrenergic blocking agents and mixtures of purines and pyrimidines. Small amounts of triethylamine and trifluoroacetic acid added to such gradients significantly improved peak shape and column performance for basic and acidic solutes. Ethoxynonafluorobutane and its mixtures with methanol have also been demonstrated to have a unique selectivity in chiral HPLC applications.