Gas Chromatography - GC Columns > Open Tubular Column Types > Page 33

Figure 18. Open Tubular Column Types

The technique of coating the walls with solid particles is again largely proprietary but stable and reproducible columns can be prepared and are commercially available. An example of the use of a PLOT column to separate and determine the impurities in a 2,3-butadiene sample is shown in figure 19. The column was 50 m long, 0.32 mm I.D. and coated with a 5 mm layer of aluminum oxide modified with potassium chloride. The separation was carried out by programming the column temperature from 100 ˚C to 200 ˚C at 6 ˚C per minute. The carrier gas employed was nitrogen and the gas velocity was 35 cm/sec. The sample (100 ml of gas) was placed on the column with a split injector and the detector used was the FID.

Figure 19 shows an excellent separation was obtained with near baseline separation for all solutes. Such a separation would allow accurate and precise quantitative assay. The analysis of hydrocarbon gasses is an important and is a control assay in almost all oil refinery quality control laboratories.

Figure 19. The Separation of the Impurities of 1,3-Butadiene