Stainless steel capillary columns

M. Konishi, Y. Mori, and T. Amano, High-performance packed glass-lined stainless steel capillary column for microcolumn liquid chromatography, Anal. Chem., 57 2235-2239 (1985). 

Harke and Drews used a 50 m long stainless steel capillary column, 0.5 mm I.D., coated with Ucon LB 550 X (polyethylene glycol) and K0H for the separation of tobacco alkaloids. A typical chromatogram of a test-mixture containing 3-pyridyl-n-propylketon, nicotine, nor-nicotine, myosmine, anabasine and nicotyrine is shown in Figure 5.1 (Tobacco alkaloids). 

Figure 20.5 illustrates the improvements in separation power in going from a packed column (6.4 X 1.8 m) to a very long but fairly wide stainless steel capillary column (0.76 mm X 150 m), to a narrow but shorter glass capillary column (0.25 mm X 50 m). Note that the resolution increases as the column becomes narrower, even when the capillary colunm is shortened. 

Fii. ao.B. Three generations in gas chromatography. Peppermint oil separation on (top) 7-in. X 6-ft packed column (center) 0.03-in. X 500-ft stainless steel capillary column (bottom) 0.25-mm X 50-m glass capillary column. [From W. Jennings, J. Chromatogr. ScL, 17 (1979) 363. Reproduced from the Journal of Chromatographic Science by permission of Preston Publications, A Division of Preston Industries, Inc.]... 

Resolution problems in the GC analysis of FA esters prompted many investigators in the past to develop capillary techniques to search for more selective stationary phases, and ultimately, to combine both approaches whenever required. In fact, FA esters were among the first substances (beyond hydrocarbons) that were successfully chromatographed on stainless steel capillary columns [355]. The most difficult separations involve different geometrical isomers, and the presence and positions of unsaturated carbon-carbon bonds. Such separations are non-trivial and justify the effort of numerous laboratories to solve these problems. 

Component Separation and Identification. Hewlett Packard 5830A and 5840A gas chromatographs fitted with glass, fused silica, or stainless steel capillary columns of various Inside diameters were used for separation of the volatiles fractions. Effluent splitters were used on occasion to permit gc effluent sniffing. Methyl silicone oil was the stationary phase of choice for most of the work, although Tween 20 and Carbowax 20M were used occasionally. 

Stainless steel columns are not lined with fused silica, which can crack or flake off when flexed or bent, thus exposing active sites. As a result, these columns can be tightly coiled to fit small GC ovens. Stainless steel capillary columns are available in three internal diameters, the standard 0.25-mm, 0.50-mm, and 0.80-mm I.D., and in lengths up to 60 m. 

Fused-Silica-Lined Stainless-Steel Capillary Columns... 

Figure 1.2 Various columns and materials employed for capillary gas chromatography (a) left 25 m x in. o.d. stainless steel capillary column in a pancake format, center 30 m X 0.25 mm i.d. aluminum-clad fused-silica column, right blank or uncoated stainless steel capillary tubing o.d. (b) 60 m x 0.75 mm i.d. borosilicate glass capillary column for EPA method 502.2 (c) 30 m x 0.25 mm i.d. fused-silica capillary column also pictured is a typical cage used to confine and mount a fused-silica column.

Figure 3.12 Metal-clad capillary columns (a) aluminum-clad capillary column (b) fused silica-lined stainless steel capillary column (lower) and polyimide-clad fused-silica capillary columns (upper), [(a) Courtesy of the Quadrex Corporation (b) courtesy of the Restek Corporation.]...

Stainless steel capillary column (50m x 0.25iran) containing Apiezon L and organo-silicone XE-60 stationary phases. 

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