Subattomole-Sensitivity Microchip Nanoelectrospray Source with Time-of-Flight Mass Spectrometry Detection

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Abstract
A microfabricated microfluidic device coupled with a nanospray tip for electrospray ionization of dilute solutions is described. The device has been interfaced with a time-of-flight mass spectrometer and evaluated for sensitive, high-speed detection of peptides and proteins. The electrospray voltage was applied through the microchip to the nanospray capillary that was attached at the end of a microfabricated channel. Fluid delivery rates were 20−30 nL min-1 through the hybridized structure without any pressure assistance. On-line microchip electrophoresis has been demonstrated and the effect of the capillary−chip junction on band broadening examined. Full mass spectra are acquired within 10−20 ms at 50−100 spectra s-1 storage rates. Detection of subattomole levels of sample from a 100 nM solution is demonstrated for infusion experiments.