Polyimide-clad fused-silica capillary columns

FIGURE 3.20 Photographs of metal-clad capillary columns (a) aluminum-clad capillary column (photograph courtesy of the Quadrex Corp.) (b) fused-silica-lined stain-less-steel capillary column (lower) and polyimide-clad fused-silica capillary columns (upper) photographs courtesy of the Restek Corporation. 

A third type of protective outer coating, stainless steel, for fused silica offers an alternative to aluminum-clad fused silica for elevated column temperatures. This technology is the inverse of that for polyimide-clad fused-silica capillary where a layer of fused silica is deposited on the inner surface of a stainless capillary. In Figure 3.19 scanning electron micrographs are displayed to compare the rough surface of stainless steel with the smooth surface of untreated fused silica and the surface of stainless steel after a micron meter layer of deactivated fused silica... 

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