MULTICHANNEL MICROCHIP ELECTROSPRAY MASS-SPECTROMETRY

Microfabricated multiple-channel glass chips were successfully interfa ced to an electrospray ionization mass spectrometer (ESI-RIS), The mic rochip device was fabricated by standard photolithographic, wet chemic al etching, and thermal bonding procedures. A high voltage was applied individually from each buffer reservoir for spraying sample sequentia lly from each channel, With the sampling orifice of the MS grounded, i t was found that a liquid flow of 100-200 nL/min was necessary to main tain a stable electrospray., The detection limit of the microchip MS e xperiment for myoglobin was found to be lower than 6 x 10(-8) M. Sampl es in 75% methanol were successfully analyzed with good sensitivity, a s were aqueous samples. The parallel multiple-channel microchip system allowed ESI-MS analysis of different samples of standard peptides and proteins in one chip.