title: Enhancement of ionization efficiency by electrochemical reaction products in on-line electrochemistry/electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry.
abstract: A miniaturized two-electrode electrochemical (EC) cell was developed and was coupled on-line with an electrospray ionization Fourier transform ion cyclotron resonance mass spectrometer (ESI-FTICR MS). Electrochemistry on-line with mass spectrometry, EC/ESI-FTICR MS, of triphenylamine (TPA), which undergoes one-electron oxidation to form a radical cation (TPA*+), demonstrates a significant sensitivity enhancement compared to ESI-FTICR MS. The on-line EC cell configuration with a stainless steel ES needle as the working electrode produces the highest sensitivity in EC/ESI-MS. The results provide evidence that, during the ES ionization, electrolytic reactions occur mainly in the ES tip region, as previously predicted. The results demonstrate that ESI-MS signal suppression by tetrabutylammonium perchlorate electrolyte, which can be a problem, is minimized in EC/ESI-MS. TPA*+ dimer tetraphenylbenzidine (TPB) can be detected by EC/ESI-MS, together with TPA*+, as TPB*+ and TPB2+. The high mass resolving power of FTICR MS was exploited to identify TPB2+ dication in the presence of [TPA*+ - H*]+ ions of the same m/z, from their respective isotopic distributions. The dimer dication TPB2+ can be detected only in EC/ESI-MS.
authors.affiliation: Department of Chemistry, University of Florida, Gainesville 32611-7200, USA.
authors.forename: Tianyi
authors.initials: T
authors.lastname: Zhang
authors.forename: Sergiu P
authors.initials: SP
authors.lastname: Palii
authors.forename: John R
authors.initials: JR
authors.lastname: Eyler
authors.forename: Anna
authors.initials: A
authors.lastname: Brajter-Toth