Author(s): Jaap de Zeeuw
Published By: Separation Science
Issue: vol. 4, issue 11
Year of Publication: 2012
Abstract: Adsorbents have unique separation characteristics. The adsorption process allows very volatile components to be retained at higher temperatures that create easier conditions to quantify very volatile compounds. Several adsorbents have found wide application in industry. Molecular sieves are used for the separation of inert gases and porous polymers based on styrene divinylbenzene are used for the separation of the more polar compounds. These adsorption materials have also been made available in capillary columns where the retention is generated by a layer of adsorbent particles on the inside wall of a capillary. Such capillaries are called PLOT (Porous Layer Open Tubular) columns and are highly efficient. They produce high theoretical plate numbers and have high operation temperatures.
The challenge of PLOT columns is to stabilize the layer as particles can be dislodged from the layer and form restrictions. Such restrictions can be measured and the values can be used to control PLOT quality. It was also possible to apply the PLOT technology in metal columns (MXT), allowing the process type of applications to take full advantage of these developments. See reference  for an historical review.