Self-made frits for nanoscale columns in proteomics.

We report here the production of self-made frits for nano-columns. The frits introduce a minor dead volume and can be placed in capillaries with a wide range of diameters (20-250 microm tested) in an extremely simple and low-cost procedure. The obtained columns appear to be comparable to "no-frit" columns with near-ideal chromatographic characteristics. We expect that this frit will be useful for the spotting of gradients onto MALDI plates but also where special ESI set-ups do not allow for "no-frit" solutions.