| Abstract
| - Two fundamental approaches for the coupling of microfabricated devices to electrospray mass spectrometry(ESI-MS) have been developed and evaluated. The microdevices, designed for electrophoretic separation, wereconstructed from glass by standard photolithographic/wetchemical etching techniques. Both approaches integratedsample inlet ports, preconcentration sample loops, theseparation channel, and a port for ESI coupling. In onedesign, a modular, reusable microdevice was coupled toan external subatmospheric electrospray interface usinga liquid junction and a fused silica transfer capillary. Thetransfer capillary allowed the use of an independentelectrospray interface as well as fiber optic UV detection.In the second design, a miniaturized pneumatic nebulizerwas fabricated as an integral part of the chip, resulting ina very simple device. The on-chip pneumatic nebulizerprovided control of the flow of the electrosprayed liquidand minimized the dead volume associated with dropletformation at the electrospray exit port. Thus, the microdevice substituted for a capillary electrophoresis instrument and an electrospray interfacetraditionally twoindependent components. This type of microdevice issimple to fabricate and may thus be developed either asa part of a reusable system or as a disposable cartridge.Both devices were tested on CE separations of angiotensinpeptides and a cytochrome c tryptic digest. Severalelectrolyte systems including a transient isotachophoreticpreconcentration step were tested for separation andanalysis by an ion trap mass spectrometer.
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