A new technique for stripping of polyimide coating from fused-silica capillaries

A novel method for the manufacture of detection windows in polyimide-coated fused-silica capillary columns is described. Concentrated fuming nitric acid at room temperature is utilized for stripping of the coating from a defined section of the capillary. The technique is particularly suitable for columns that have a heat sensitive coating on the inner wall or for columns that contain an immobilized hydrogel sieving-matrix. A column holder for the simultaneous preparation of detection windows in an array of more than 100 capillaries is also reported.