SUMMARY

Electrospray Ionization (ESI) is a technique that permits the ionization of large proteins and biomolecules without fragmenting them, which allows them to be identified via Mass Spectrometry (MS). It has the potential of permitting the identification of transient intermediate products in biological processes in situ, which would provide great insight to researchers in the growing fields of proteomics and metabolomics. However, this application presents a technical challenge in that most relevant biochemistry occurs in aqueous solutions with high salt content, which makes successful identification of analytes by ESI-MS difficult.

This thesis presents the design, fabrication, and characterization of a microdialysis-electrospraying system that could overcome this current limitation by desalting samples while minimizing transit time, which optimizes analysis temporal resolution. The microdialysis (MD) component design is based on a theoretical analysis of dialysis and microfabricated with processes that include plasma etching and e-beam deposition. The efficiency of the desalting module is demonstrated with salt concentration experimental data that agrees with analytical and computational predictions. Mass spectrometry analyses of proteins in solution also corroborate its performance.