Developments in stationary phase technology for gas chromatography

In gas chromatography (GC), the main driver for the separation is the stationary phase, which is deposited on the inside wall of capillary columns. Many developments have taken place in the past 20 years. The stationary phases used in GC are liquid phases, adsorbents and, sometimes, a combination. Adsorbents are widely used and show highly selective separations, especially for gases and volatiles. Adsorbents, such as aluminum oxide and the molecular sieve, have found wide application in GC for hydrocarbon and permanent gases. A new generation of in-situ adsorbents, based on divinylbenzene, silica and carbon, show improved performance with respect to mechanical stability, temperature range and inertness, and they are used for difficult applications where their selectivity is exploited. Unique interactions are obtained with a multi-layer technology, called Lowox. Liquid phases are usually polymers based on polydimethylsiloxane/carborane/glycol/divinylbenzene with different degrees of substitution. Technologies are developed by chemical bonding and cross-linking of such polymers to stabilize liquid phases, making the stationary phase more robust and suitable for trace and high-temperature analysis. Special groups are incorporated to elute basic, acidic, chiral compounds and FAME (fatty acid methyl ester) compounds. The newest technologies allow the inclusion of special stabilizing groups to increase thermal stability for non-polar as well as polar stationary phases; technologies, such as sol gel, allow the in-situ preparation of bonded liquid phase layers. The behavior of these stabilized adsorbents and liquid phases is discussed in detail, as well as their current application. (C) 2002 Published by Elsevier Science B.V. All rights reserved.