ABSTRACT
Only three parameters of high-performance liquid chromatography (HPLC) columns can be miniaturized to lead to micro-HPLC: the internal diameter, the length, and the mean diameter of the column packing material. The quality factors of silica gel are equally important for analytical, preparative, and micro-HPLC packing materials, Considering the small amount of silica gel needed for micro HPLC, the most stringent quality requirements can be observed. One-micrometer particles seem about the limit that can be handled by traditional techniques of filtration, sieving, derivatization, viewing under a light microscope, etc. A very important new technique for packed fused silica capillaries uses tubing with an inner wall elastic coating. One of the advantages of fused silica tubing is the highly polished nature of the wall. A very important new technique for packed fused silica capillaries uses tubing with an inner wall elastic coating. This holds the packing structure and leads to highly efficient columns with excellent stability.
