Publications by authors named "Alexandre V Loboda"

We describe a novel ion source for analytical mass spectrometry based on femtosecond laser ionization at pressures at and above atmospheric and characterize its performance when coupled to a tandem quadrupole/time-of-flight mass spectrometer. We assess source saturation limits, ionization and sampling efficiencies, the effective ionization volume, and limits of detection. We demonstrate 100% efficient ionization for a set of organic compounds and show that the degree of ion fragmentation over a range of laser powers is favorable compared to electron impact ionization, especially in that a substantial parent ion signal is always observed.

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Ultraviolet photodissociation (UVPD) was evaluated as a technique for generating ion fragmentation information that is alternative and/or complementary to the information obtained by collision-induced dissociation (CID). Ions trapped in a pressurized linear ion trap were dissociated using a 355 nm or a 266 nm pulsed laser. Comparisons of UVPD and CID spectra using a set of aromatic chromophore-containing compounds (desmethyl bosentan, haloperidol, nelfinavir) demonstrated distinct characteristic fragmentation patterns resulting from photodissociation.

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In this work, a new absorbing candidate, rhodamine (R) 575, is described, which forms the basis of a binary matrix operating at 532 nm. Analyte ionization is found to be much more efficient when the dye is combined with a proton donor such as hydrochloric acid or alpha-cyano-4-hydroxycinnamic acid, or a proton acceptor such as sodium hydroxide. This makes the matrix more generic than many others that have been tried.

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