A simple and efficient frit preparation method for one-end tapered-fused silica-packed capillary columns in nano-LC-ESI MS.

A novel frit preparation method for one-end tapered-fused silica-packed capillary columns in nano-LC-ESI MS was developed. A hollow-fused silica capillary column with a tapered tip as nano-spray emitter was filled with 5 microm C(18) beads, and then a sintered frit about 0.25 mm in length was prepared at the tip by butane flame. A stainless steel protection tube with 0.5 mm id was used to control the length of the frit and to protect the packed C(18) beads behind the sintered frit during the sintering. C(18) sintered frits were evaluated by BSA tryptic digests with nano-LC-LTQ. The sintered frits did not produce post-column band broadening due to very small volume (about 0.2 nL) and did not produce adsorption to sample. The sintered frit columns had good separation reproducibility and separation performance compared with self-assembled particles frit columns and commercial columns.