GC Stationary Phase

GC methods are divided into two classes depending on the nature of stationary phases; gas-solid chromatography (GSC) and gas-liquid chromatography (GLC). GSC has solid adsorptive material and solute particles are removed from mobile phase by electrostatic forces. GLC has a thin layer of liquid coated or bonded on the surface of an inert particle or on the walls of the column where solute particles are retained in the liquid phase based on their partition coefficients. The primary necessity of a stationary phase is to provide sample separation sustaining phase integrity over a reasonable period of time. It should be stable for the chemical and thermal changes. Selectivity, peak symmetry, analysis time, degree of separation, peak tailing are few parameters that should be considered before choosing a stationary phase. Bentone 34 is a bentonite treated with dimethyloctadecylammonium salts which has broad applications in GC. It can differentiate between isomers of many aromatic compounds and cycloalkane derivatives. It can also be modified with silicone oil in order to improve the peak symmetry.

Synthesized specifically to be purer, of narrow molecular weight range, and without trace catalysts or impurities for use as a GC stationary phase.

Bentone 34 may be used as column coating, using a benzene-methanol (9:1) mixture as dispersion agent to analyse cresol mixtures.