Separation of Low-boiling Hydrocarbons by Gas Chromatography using Packed Capillary Columns

Abstract

BY modifying the method described by Desty et al.1 for drawing glass capillaries, we have succeeded in making packed columns having an inner diameter comparable with that of capillary columns, which will be referred to here as ‘packed capillaries’. A capillary packed with an adsorbant is particularly suited for separating low-boiling hydrocarbons at room temperature, an operation requiring very low temperatures when carried out with a conventional capillary column. Filling the capillary with an adsorbant is performed thus: a carefully cleaned steel wire of 1 mm. diameter is pushed through a glass tube having an inner diameter of 2.2 mm. and the empty space between the wire and the tube wall filled with the adsorbant. Then placing the tube in a horizontal position and removing the wire carefully the glass is drawn to a capillary of 0.3 mm. inner diameter, using Desty's method. The adsorbant used in our experiments was alumina produced by calcining for 9 hr. at 400° C. hydragillite (CAMAG Chemie-Erzeugnisse und Adsorptionstechnik AG., Muttenz, Switzerland) [γ-Al(OH)3], having a grain size of 0.10–0.15 mm. Afterwards the column was flushed for 24 hr. at 120° C. by a stream of dry hydrogen, in order to remove traces of water which might have been adsorbed by the alumina during the filling and drawing operation.