Complete large-molecule high-resolution mass spectra from 50-femtomole microvolume injection.

ABSTRACT

For electrospray ionization in Fourier-transform mass spectrometry, direct injection of 5×10(-14) mol (0.5 µL of 100 nM from a microvolume sample valve) of ubiquitin (8565 Da) into the flowing solvent stream yields a spectrum with 851 signal-to-noise ratio, 2-ppm mass accuracy, and isotopic resolution. Gated trapping for 100 µs from a 0.15-µL/min injection of 20-µM ubiquitin consumes 5×10(-18) mol, which produces a spectrum with 231 signal-to-noise ratio and τ;3×10(5) resolving power.