lithium-chloride and acetonitrile

The 3,5-dimethylphenylcarbamate derivatives of cellulose bearing 3-(triethoxysilyl)propyl residues were immobilized in a capillary format onto a monolithic silica support by intermolecular polycondensation of the triethoxysilyl groups. The resulting columns were used for chiral separations using capillary electrochromatography. The effects of the synthesizing solvent, the selector coating procedure, the chiral selector concentration onto the silica monolith and the mobile phase pH value, on the separation of enantiomers were studied. The column-to-column reproducibility and stability also were evaluated. A test set of 14 chiral substances, including acidic, neutral, bifunctional and basic compounds, was used to investigate the effects of the factors mentioned above. Twelve pairs of enantiomers showed enantioselectivity at some of the different conditions tested. The column-to-column repeatability was satisfactory, and the prepared columns were stable under the adopted analysis conditions.

Topics: Acetamides; Acetonitriles; Capillary Electrochromatography; Cellulose; Hydrogen-Ion Concentration; Lithium Chloride; Pharmaceutical Preparations; Phenylcarbamates; Reproducibility of Results; Silicon Dioxide; Stereoisomerism

A method of accurate mass determination of phosphoramidites is described. The commonly used methanol/water/acid system was replaced by LiCl-containing acetonitrile and the concentrations of LiCl, poly(ethylene glycol), and phosphoramidite samples were optimized.

Topics: Acetonitriles; Lithium Chloride; Macromolecular Substances; Mass Spectrometry; Models, Chemical; Molecular Biology; Organophosphorus Compounds; Polyethylene Glycols; Polymers; Reproducibility of Results; Spectrometry, Mass, Electrospray Ionization