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.
- Capillary electrochromatography
- Two-step laser mass spectrometry
- Mass spectrometry
- Polycyclic aromatic hydrocarbon