Document Type

Thesis

Publication Date

1996

Disciplines

Chemistry

Advisor

Robert Fulton

Abstract

Due to the widespread use of chromatography, improving efficiency in chromatography is continually an area of interest. Researchers have suggested that the method of column temperature control influences efficiency. To insure reproducible retention times, HPLC columns are often thermostated with a water jacket. Under such conditions, however, a radial thermal gradient may arise from the heat produced by friction between the stationary and mobile phases. If the core of the column is allowed to warm up while the walls are kept at a constant temperature, the solute in the core of the column will elute faster than will that at the walls. This phenomenon creates a wider band of solute leaving the column, which results in poorer efficiency. Insulating the column should eliminate the radial thermal gradient because the column is allowed to heat up uniformly, and air thermostating the column should reduce the gradient. Experiments indicate that the insulated and air thermostated columns yield better efficiencies than does the water thermostated column. A mathematical model generated to compare the efficiencies of columns that contain radial thermal gradients with those that do not shows that radial thermal gradients significantly reduce efficiency.

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