The Column Constants of Alcohols on Carbowax 35000 Columns

Abstract

The equation (Eq.1) proposed by Krisnangkura et al. [1] has been used successfully in forecastingthe solutes retention times of the capillary column.

Ink = a + bn + c/T + dn/T        (1)

The major difficulty in using Eq. (1) is the determination of the 4 constants (a, b, c and d), which istedious and time consuming. It is speculated that columns of the same inside diameter coated with the samestationary phase and having the same film thickness, should have the same numeric values. However, inpractice, it is extremely difficult to control all columns to have the same phase ratio. Consequently, the avalue of each column is slightly different. Therefore, at this moment, only the numeric value of a has to bere-determined and only one injection of the reference mixture is required. Thus, the method of determinationof the 4 constants is much simplified.

Although coating efficiency is relatively low (20%), it is good enough for the study of the 4 thermodynamicconstants.

Keywords : Gas Chromatography / Carbowax / Column Constants / Capillary Column / StationaryPhase / Alcohol