Tubing capillary columns

Another factor which has improved the quality of the capillary columns a great deal and encouraged their application, is the achievement in chemically bonding the liquid phase to the internal surface of the fused silica capillary tubing. Capillary columns of extraordinarily high quality and capability have resulted from improved quality of the liquid phases ami cross-linking of liquid phases. 

Most GC analyses, and almost all that are concerned with trace quantitative analysis, are nowadays conducted using unpacked (open tube) capillary columns the following discussion will be mainly concerned with these. In this regard, a great deal is owed to Golay (see the accompanying textbox), who was responsible for both the underlying theory and the first practical demonstrations. 

For capillary columns fused siHca is the material of choice for the column container. It has virtually no impurities (<1 ppm metal oxides) and tends to be quite inert. In addition, fused siHca is relatively easily processed and manufacture of columns from this material is reproducible. In trace analysis, inertness of tubing is an important consideration to prevent all of the tiny amounts of sample from becoming lost through interaction with the wall during an analysis. 

Capillary columns are fabricated from thin-walled stainless steel, glass, or high-purity fused silica tubing (the last is preferred for its inertness). Typical dimensions of the columns, which are coiled, are 25-200 m long and 0.2-0.5 mm i.d. 

Capillary column A narrow bore tube (0.25-1 mm ID) typically 30-100 m long (usually of deactivated fused silica), whose walls are coated with a liquid stationary phase to produce high-efficiency separations (N > 100,000). 

MaStovska et al5 demonstrated the use of a 5-m GC capillary column surrounded by a tube of resistively heated steel to raise the column temperature more rapidly and uniformly than a conventional GC oven. They analyzed 15 organophosphoms... 

Rasmussen [82] describes a gas chromatographic analysis and a method for data interpretation that he has successfully used to identify crude oil and bunker fuel spills. Samples were analysed using a Dexsil-300 support coated open tube (SCOT) column and a flame ionisation detector. The high-resolution chromatogram was mathematically treated to give GC patterns that were a characteristic of the oil and were relatively unaffected by moderate weathering. He compiled the GC patterns of 20 crude oils. Rasmussen [82] uses metal and sulfur determinations and infrared spectroscopy to complement the capillary gas chromatographic technique. 

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