Abstract
The steam carrier adsorption gas chromatography was applied effectively to the separation of carboxylic acids, especially in dilute aqueous solution.
The separation column was prepared by baking at 500°C for 5 minutes a glass tube (1.83.7 mmφ × 2.64.0 m) packed with Chromosorb P AW 30/60 with 3% phosphoric acid, so that it might be very stable against organic acids and steam carrier at a considerably high temperature.
Fatty acids from C2 to C18, benzoic acid, salicylic acid and lactic acid were tested in 0.1%0.1 ppm aqueous solution, whereby insoluble materials were supplied as their alkaline metal salts which showed chromatograms identical to those of the free acids in organic solvents such as carbon tetrachloride.
Elution peaks were almost symmetrical, especially at lower temperature. A satisfactory separation with 0.120.17 cm of H. E. T. P. was obtained for lower fatty acids.
Retention times in this adsorption gas chromatography were very short ; enanthic and n-caproic acids were eluted in 35 sec. at 170°C, and stearic and palmitic acids were eluted in 90 sec. at 225°C, both with only slight decrease of separability.
Identification of fatty acids in their extremely dilute aqueous solution was achieved by this method : for example, 0.1 ppm of fatty acids from lower to enanthic and also 1 ppm of palmitic acid were detected by using a hydrogen flame ionization detector.
