Structural characterization of drugs and oxygenated metabolites by laser microprobe mass spectrometry (LAMMA)

Vaeck, Luc Van; Espen, P. Van; Gijbels, R.; Lauwers, W

doi:10.1002/bms.1200160121

Cited by 12 publications

(3 citation statements)

References 4 publications

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“…The most striking results are found for tryptamine-based analogues (cf. Evidence for radical molecular ions from fragments is also found for N-oxides in the positive and negative ion detection mode [28]. 4), but the main trends are generally followed.…”

Section: Structural Characterization Of Organic Compounds By Lmmsmentioning

confidence: 87%

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Laser microprobe mass spectrometry: Possibilities and limitations

et al. 1990

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Laser microprobe mass spectrometry (LMMS) offers a great potential for inorganic analysis and speciation as well as for organic structural characterization. This remarkable flexibility makes the results critically dependent on the experimental conditions, however, so an exact description is hard to achieve, since inaccessible local parameters are involved. The paper deals in detail with this aspect, which is often neglected but remains essential for making LMMS acceptable as analytical tool. Our methods of procedure are presented in the context of instrumental aspects and experimental evidence. Tentative hypotheses for desorption and ionization in LMMS provide an adequate framework for interpreting results consistently. Selected examples illustrate the potential gained from our experimental procedure as well as the limitations imposed. For organic compounds, analysis of pure products and simple mixtures, and microprobe applications are highlighted. Improved differentiation of inorganic compounds is also shown.The use of lasers in MS dates back about two decades in both inorganic and organic analysis. On the one hand, photon interaction is exploited for overall elemental determinations in non-conducting solids, for instance as an alternative to sparksource excitation [1]. On the other hand, laser desorption is widely appreciated as a so-called soft ionization method for thermolabile organics, yielding cationized molecules and the virtual absence of fragmentation [2]. These instruments have been used mainly in individually developed set-ups.

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Section: Structural Characterization Of Organic Compounds By Lmmsmentioning

confidence: 87%

“…Indeed, external calibration has permitted key information to be obtained about generation of radical molecular and fragment ions [26][27][28], for instance. So-called missing shots are virtually inevitable during particle analysis.…”

Section: Fig 2 Time Selectivity Of Lmms Instrumentation Compared Wimentioning

confidence: 99%

Laser microprobe mass spectrometry: Possibilities and limitations

et al. 1990

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“…The structural assignment of the organic fragments ( Figure 5) is indicated on the mass spectra but their formation pathways have been discussed before. [46][47][48] Looking at the number of scans and the signal-to-noise (S/N) ratio, it is clear that the new ion optics yield a detection sensitivity that is improved by a factor of 10. There is a limited difference in flight times for ions of a given m/z value when the use of the new ion optics is compared with the original optics, but this difference is negligible when compared with the reflection time in the cell.…”

Section: Experimental Evaluationmentioning

confidence: 99%

A New Electrostatic Transfer Line for Improved Transmission in Fourier Transform Laser Microprobe Mass Spectrometry with External Ion Source

Vaeck

Espen

Gijbels

et al. 2000

Eur J Mass Spectrom (Chichester)

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The efficient extraction and transfer of ions from an external ion source outside the magnet and their injection through the inhomogeneous fringing field becomes a key factor in the micro-analytical application of Fourier transform mass spectrometry (FTMS) instruments with an external ion source. This paper reports on a new ion transfer line with static electrical fields for a source at a distance of 131 cm from the cylindrical ion cyclotron resonance (ICR) "Infinity" cell in an unshielded 4.7 Tesla superconducting magnet. Basically, ions are accelerated to 2-3 kV, transported through a time-of-flight (TOF) system and decelerated at the entrance of the magnet. The size of the system, the magnetic stray field and the significant electrical field gradients require careful optimisation of the simulations with the SIMION software. According to our calculations, the new ion transfer line should allow transport and trapping of ions initially emitted with an angle of up to 35°with the normal, as opposed to 5°with the former commercial transfer line with improved cylindrical front optics. The design has been experimentally verified using focused laser desorption/ionisation of solids. The data on reference compounds have demonstrated that the sensitivity with the new transfer line increases by a factor of 10. A substantial gain of sensitivity is also expected for other ionisation methods producing ions with a more isotropic angular emission than focused laser irradiation. The new ion optics are fully compatible with the existing hardware so that conversion becomes a minor operation.

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