Characterizing synthetically prepared packing materials and standard monolithic columns by inverse size exclusion chromatography

Characterizing the analytical column is the first step in determining whether the column is suitable for the work\u27s aim, or not. This work will be devoted to characterizing two kinds of columns: the normal practical packing column and the monolithic column. The Inverse Size Exclusion Chromatography (ISEC) method has been applied to study and characterize these columns by using a long series of standard polystyrene samples of narrow molecular weight distribution. These samples have been carefully chosen to cover a wide range of molecular weight between 5 X 102 up to 2 X 106 Dalton. The former columns were packed with synthesized and prepared materials that were made at Oak Rage National Laboratory (ORNL) by Dr. S. Dai and his student Mr. C. Liang. The monolithic columns were given to Prof. G. Guiochon as a generous gift from MERCK Company. Our work on these columns will be focused on five important characteristics: efficiency, pore-size diameter, pore-size distribution, porosity, and excluded molecular weight. In fact, by applying ISEC for these columns once by CH2CL2 and another by THF, we should acquire more or less the same results (except the efficiency). One of the prepared packing materials that investigated has a reasonable efficiency, as a prepared material, around 3200 plate; the other characters reveal very consistent values in both runs. The other four materials have poor efficiency (less than 2000), very different values when the run is shifted from CH2CL2 to THF. We conclude that these prepared materials either cannot fit and achieve the boundaries and the necessary conditions to be characterized by ISEC, or that they need to be improved in some points concerning their structure. The monolithic columns showed rather excellent and reliable values for SD\u27s and RSD\u27s, as well as, very high efficiency over 4500 plate comparing with the normal packing materials. We have to be very careful when we deal with the monolithic columns, especially, regarding the purity grade of the sample and the solvents. Dealing with unfiltered reagents causes a kind of contamination, which affects the characters of the columns

Photoinitiated polymerisation of monolithic stationary phases in polyimide coated capillaries using visible region LEDs

The spatially controlled synthesis of poly(glycidyl methacrylate-co-ethylene dimethacrylate) monolithic stationary phases in polyimide coated fused silica capillaries by visible light induced radical polymerisation using a three-component initiator and a 660 nm light emitting diode (LED) as a light source is presented here

Adsorption equilibria of butyl- and amylbenzene on monolithic silica-based columns

The adsorption isotherms of butyl- and amylbenzene on silica monolithic columns were measured by frontal analysis. The external, internal and total porosities of these columns were determined by inverse size-exclusion chromatography. The adsorption isotherms are concave upward in the entire concentration range investigated. They were fitted to the anti- Langmuir model, an unusual model in liquid-solid and liquid-liquid phase equilibria. Band profiles under overloaded conditions were recorded. They were in good agreement with the profiles calculated using the lumped pore diffusion model of chromatography and these adsorption isotherms