Development of novel interfaces for combining liquid chromatography with matrix-assisted laser desorption ionization mass spectrometry

The analysis of complex proteomic samples is dominated by LC-MS techniques. MALDI-MS offers complementary performance to ESI-MS methods, though the latter is more readily interfaced with liquid chromatography. An offline LC-MALDI interface was developed to facilitate protein profiling experiments. This interface uses "impulse-driven deposition", a unique deposition technique developed to achieve non-contact fluid spotting of a wide range of droplet volumes. This interface technology was applied to the LC-MALDI analysis of a tryptic digest of E. coli protein extract.;Many aspects of LC-MALDI experiments can be optimized to achieve greater proteomic detail. Careful optimization LC-MALDI parameters such as column loading capacity, degree of fraction collection, and the MALDI-MS analysis can enhance the success of protein profiling experiments.;The impulse-driven deposition technique was combined with a heated-droplet technology to create a new interface capable of offline fraction collection of microbore LC separations. The high loading capacity of microbore separations allows large quantities of sample to be separated; the unique impulse-drive/heated-droplet fraction collection allows these separations be recorded on standard MALDI plates. This interface was used in the analysis of post-translational modifications of alpha-casein, and with the high loading capacity available to the analysis, all phosphorylation sites of the protein were identified.