A novel two-laser interface for coupling capillary electrochromatography with ion-trap time-of-flight mass spectrometry

Abstract

An interface has been developed for the hyphenation of capillary electrochromatography (CEC) with mass spectrometry (MS). Chromatographic eluate vaporization and selective analyte ionization occur within a quadrupole ion-trap, which permits significant instrument simplification when compared with the atmospheric pressure interfaces typically used for CEC-MS. Vaporization is achieved using laser desorption at 1064 nm while ionization is accomplished through UV photoionization. This two-step approach, through ionization laser wavelength selection, can provide ultratrace analysis with high selectivity. The mass spectrometer is a hybrid ion-trap time-of-flight (TOF) instrument in which the ion-trap is used in radio frequency-only mode, with DC-pulse ejection, to provide decoupling of the different timescales required for CEC separation and TOF mass analysis. The ion-trap is capable of accumulating ions over multiple laser shots. The mass resolution of the demonstration instrument was circa 1500. Preliminary CEC-MS runs have been recorded for mixtures containing polycyclic aromatic hydrocarbons. A concentration detection limit of 500 nM, for naphthalene in acetonitrile, has been determined for the interface.

Direct and fast detection of chlorothalonil in soil samples using laser desorption VUV single photon post-ionization mass spectrometry

“…18,19 In the ionization step, gas-phase molecules in the desorbed plume of neutrals are typically ionized by either VUV single photon ionization (VUV-SPI) or ultraviolet resonant enhanced multiphoton ionization (UV-REMPI). 26,27 It is absolutely different from surface assisted laser desorption ionization (SALDI) mass spectrometry, in which the modified surface of a sample plate assists in transferring energy to the analytes for more efficient desorption and ionization. 18 While VUV single photon ionization is a nearly universal ionization method for compounds with ionization energies lower than this photon energy.…”

Laser Desorption/Ablation Postionization Mass Spectrometry: Recent Progress in Bioanalytical Applications

“…Although there have been several applications on drugs and biomolecules such as peptides and amino acids, the 7.87 or 10.5 eV laser used in most VUV L2MS has made this methodology less robust for analytes with higher ionization potentials (Akhmetov et al, 2010). To enhance the mass signal of analytes, efforts have been devoted into the introduction of nanomaterial matrix, higher photon energy laser sources, derivatization of the analyte to lower its ionization potential, and the development of a novel interface, which bears the combination of laser sources and capillary electrochromatography (Heinbuch et al, 2005; Edirisinghe et al, 2007; Simpson et al, 2014; Lu et al, 2018a). Another challenge remains to develop methods that will reproducibly determine trace amount analytes in natural matrixes while keeping balance within the laser power, wavelength, and the delay time between the desorption and ionization lasers.…”

Recent advances in microscale separation

“…Simpson et al. developed an interface for the hyphenation of CEC with MS. Wu et al. developed a pCEC method for the analysis of urine metabolites in coupling with QTOF‐MS.…”