Use of small-diameter capillaries for increasing peptide and protein detection sensitivity in capillary electrophoresis-mass spectrometry

摘要: The use of small ID capillaries is shown to provide a substantial increase in sensitivity for capillary electrophoresis-electrospray ionization/mass spectrometry (CE-ESI/MS). In comparison using ranging from either 100 10 microns or 50 5 and chemically modified with aminopropylsilane, 25- 50-fold was observed both peptide protein mixtures. This enhanced solute allowed the detection approximately 150 attomoles melittin (2845 Da) selected ion monitoring 600 carbonic anhydrase (29,157 while scanning CE-MS quadrupole mass spectrometer. For mixture, spectra sufficient quality precise molecular weight determination (< = 0.05%) were obtained attomole injections capillary. diameters can be primarily attributed reduced flow rate buffer other background constituents into electrospray source, which allows greater sample ionization efficiency. A model that qualitatively accounts results presented, but quantitative agreement precluded due difficulties accounting contributions liquid sheath used source. observation ESI/MS appears function as concentration-sensitive detector under many conditions large-diameter capillaries. transition occurs, however, regime where functions flow-sensitive small-diameter capillaries, ESI current limited by delivery source charge carrying species solution. These suggest analysis at low subattomole levels should obtainable alternative types spectrometers.