Pillar array columns for peptide separations in nanoscale reversed-phase chromatography.

Reversed-phase chromatography is the most common technique for separation of tryptic peptides. In this short communication, we describe the optimization of sample loading and separation parameters for a novel micromachined column and provide a detailed description on the performance and reproducibility of this separation system. Tryptic digest of a mixture of seven proteins with diverse mass and isoelectric point was used as a test sample. The methods developed and used are straight-forward; by using well-balanced, combined-step gradients an optimal distribution of peptides on the column could be achieved throughout the complete gradient window. The potential use of the column is exceptional due to the low back-pressure, better distribution of peptides over the separation window, enhanced stability and reproducibility of retention times, and the prolonged lifetime of columns compared to conventionally packed nano-HPLC column. The higher identification rates have been demonstrated through measurements of HeLa cell lysates under identical chromatographic conditions on the pillar array and packed-bed columns.