An enhanced microfluidic chip coupled to an electrospray Qstar mass spectrometer for protein identification

The combination of microfabricated fluidic systems (mu FAB) and electrospra y mass spectrometers (ESI-MS) will provide multiplexed and integrated analy tical systems for proteins and other;biomolecules, Implementation of this n ovel approach requires the development of robust and user-friendly mu FAB d evices. Here, we present new approaches that improve the robustness, user f riendliness and performance of mu FAB devices coupled to MS. First, we pres ent the development of a convenient mount to connect a mu FAB device to the ESI-MS and the incorporation of filters in the reservoirs and exit of the mu FAB. This mount facilitates interfacing and significantly reduces the ch emical noise observed by the MS. Furthermore, we demonstrate improvements i n sample handling and delivery by using either a nonaqueous electrolyte or a cationic coating on the surfaces in the mu FAB device and transfer capill ary. These improvements are applied to protein analysis by continuous infus ion of proteolytic digests.