Uniformity of ionization response of structurally diverse analytes using a chip-based nanoelectrospray ionization source

Rapid Commun Mass Spectrom. 2005;19(21):3139-42. doi: 10.1002/rcm.2182.


The major drawback of liquid chromatography/mass spectrometry (LC/MS) for the analysis of mixtures is the non-quantitative nature of these studies. The ionization efficiency of the various components in the mixture (e.g., a compound and its metabolites) can vary greatly and, therefore, relative intensities of signals cannot be related to relative abundance. A chip-based nanoelectrospray ionization source was used to compare the ionization efficiencies of compounds with different physical-chemical characteristics. The data indicate that the ionization efficiencies vary much less with the chip-based device than by LC/MS. This was ascribed to the generation of a much higher electric field around the nozzles, which supplies a large excess of protons to the small droplets and reduces/eliminates the differences in the ionization efficiency for the analytes.

MeSH terms

  • Animals
  • Antipsychotic Agents / analysis
  • Antipsychotic Agents / chemistry
  • Glutathione / analysis
  • Glutathione / chemistry
  • Humans
  • Microchip Analytical Procedures*
  • Nanotechnology / methods*
  • Pharmaceutical Preparations / chemistry
  • Pharmaceutical Preparations / metabolism*
  • Piperazines / analysis
  • Piperazines / chemistry
  • Spectrometry, Mass, Electrospray Ionization / instrumentation
  • Spectrometry, Mass, Electrospray Ionization / methods*
  • Thiazoles / analysis
  • Thiazoles / chemistry


  • Antipsychotic Agents
  • Pharmaceutical Preparations
  • Piperazines
  • Thiazoles
  • ziprasidone
  • Glutathione