Mechanism of Collisional Heating in Electrospray Mass Spectrometry: Ion Trajectory Calculations

in Journal of Physical Chemistry A (2001), 105

To simulate the multicollisional heating process taking place in the intermediate pressure region of an electrospray source, ion trajectory calculations have been preformed by introducing in the SIMION ... [more ▼]

To simulate the multicollisional heating process taking place in the intermediate pressure region of an electrospray source, ion trajectory calculations have been preformed by introducing in the SIMION program a subroutine for handling the collision dynamics. The simulated internal energy distributions are compared with already available experimental distributions obtained by the "survival ion yield" method. [less ▲]

Optimisation and Use of Tandem-in-Time Mass Spectrometry in Comparison with Immunoassay and Hrgc/Hrms for Pcdd/F Screening

in Chemosphere (2001), 43(4-7, May-Jun), 417-24

Rapid screening of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans using quadrupole ion storage tandem-in-time mass spectrometry (QISTMS) conjointly with polyclonal antibody ... [more ▼]

Rapid screening of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans using quadrupole ion storage tandem-in-time mass spectrometry (QISTMS) conjointly with polyclonal antibody immunoassay has been considered. The optimisation of the fragmentation of the parent ion in the trap has been completed. The analysis of fly ashes from a municipal waste incinerator contaminated at different levels has then been realised. Results obtained using QISTMS, HRMS and immunoassay are compared. [less ▲]

La Problématique des Dioxines, Furannes et PCBs

Conference (2000, March)

Gas Phase Thermal Denaturation of an Oligonucleotide Duplex and Its Complexes with Minor Groove Binders

in Rapid Communications in Mass Spectrometry : RCM (2000), 14(6), 464-467

Electrospray ionization with in-source collisionally induced dissociation has been used to probe the gas phase stability of an oligonucleotide duplex and its complexes with some minor groove binding drugs ... [more ▼]

Electrospray ionization with in-source collisionally induced dissociation has been used to probe the gas phase stability of an oligonucleotide duplex and its complexes with some minor groove binding drugs. On the basis of the arguments developed in detail by Drahos et al. (J. Mass Spectrom. 1999; 34:1373), this type of experiment can also be described as 'thermal denaturation in the gas phase'. We found that the gas phase denaturation curves were very similar to the solution phase denaturation curves determined by the traditional UV spectrophotometric method and, by analogy with the melting temperature T(m) which characterizes the stability in solution, we define a melting voltage V(m) to characterize the stability in the gas phase. A comparison of the T(m) and V(m) relative values suggests that the structure of the complexes is conserved during the electrospray process which transfers the ions from the solution to the gas phase. [less ▲]

New High Capacity Disposable Silica Columns (HCDS) instead of GPC for Automated Clean-up of Biological Fatty Matrices in PCDD/Fs and cPCBs Analysis.

in Organohalogen compounds (2000), 45

Les Dioxines

Article for general public (1999)

Interaction between Antitumor Drugs and a Double-Stranded Oligonucleotide Studied by Electrospray Ionization Mass Spectrometry

in Journal of Mass Spectrometry [=JMS] (1999), 34(12), 1328-1337

Electrospray ionization mass spectrometry was used to investigate the complex formation between a double-stranded oligonucleotide and various antitumor drugs belonging to two categories: intercalators ... [more ▼]

Electrospray ionization mass spectrometry was used to investigate the complex formation between a double-stranded oligonucleotide and various antitumor drugs belonging to two categories: intercalators (ethidium bromide, amsacrine and ascididemin) and minor groove binders (Hoechst 33258, netropsin, distamycin A, berenil and DAPI). The goal of this study was to determine whether the relative intensities in the mass spectra reflect the relative abundances of the species in the solution phase. The full-scan mass spectra suggest non-specific binding for the intercalators and specific binding for the minor groove binders. The preferential stoichiometries adopted by each minor groove binder were determined by studying the influence of the drug concentration on the spectra. We obtained 2:1 > 1:1 for distamycin, 1:1 > 2:1 for Hoechst 33258 and DAPI and only the 1 : 1 complex for netropsin and berenil. These features reflect their known behavior in solution. The compared tandem mass spectra of the 1 : 1 complexes with Hoechst 33258 and netropsin, when correlated with published crystallographic data, suggest the possibility of inferring some structural information. The relative binding affinities of the drug for the considered duplex were deduced with two by two competition experiments, assuming that the relative intensities reflect the composition of the solution phase. The obtained affinity scale is netropsin > distamycin A > DAPI > Hoechst 33258 > berenil. These examples show some of the potential uses of mass spectrometry as a useful tool for the characterization of specific drug binding to DNA, and possibly a rapid drug screening method requiring small amounts of materials. [less ▲]

Thermal Energy Distribution Observed in Electrospray Ionization

in Journal of Mass Spectrometry [=JMS] (1999), 34

A new method was developped which fits a thermal internal energy distribution to ions formed by electrospray ionization. The molecular ion survival yield was measured and determined by RRKM calculations ... [more ▼]

A new method was developped which fits a thermal internal energy distribution to ions formed by electrospray ionization. The molecular ion survival yield was measured and determined by RRKM calculations as a function of temperature. The "characteristic" temperature was determined when the calculated and measured molecular survival yields were equal. The validity of the method was also checked performing blackbody infrared radiation and on-resonance excitation experiments on a Fourier transform ion cyclotron resonance instrument with benzylpyridine salts and leucine enkephalin. [less ▲]

Optimization of biosurfactant lipopeptide production from Bacillus subtilis S499 by Plackett-Burman design

in Applied Biochemistry and Biotechnology (1999), 77-9

Bacillus subtilis S499 is well-known for its ability to produce two families of surfactant lipopeptides: Iturin A and Surfactin S1. Fermentation optimization for this strain was performed to amplify the ... [more ▼]

Bacillus subtilis S499 is well-known for its ability to produce two families of surfactant lipopeptides: Iturin A and Surfactin S1. Fermentation optimization for this strain was performed to amplify the surfactant production. Ten active variables were analyzed by two successive Plackett-Burman designs, consisting respectively of 12 and 16 experiments to give an optimized medium. The amount of biosurfactant lipopeptides in the supernatant of a culture carried out in this optimized medium was about five times higher than that obtained in nonoptimized rich medium. The analysis of the surfactant molecules produced in such optimized conditions has revealed the presence of a third family of lipopeptides: the fengycins. The time-dependent production of these three families of molecules in bioreactors showed that surfactin S1 is produced during the exponential phase and iturin A and fengycins during the stationary phase. [less ▲]

Supercritical fluid extraction of polychlorinated dibenzo-p-dioxins from fly ash: the importance of fly ash origin and composition on extraction efficiency

in Journal of Chromatography. A (1998), 819(1-2), 187-195

Supercritical fluid extraction (SFE) of polychlorinated dibenzo-p-dioxins (dioxins) from by ash samples, collected at different municipal waste incinerators, was investigated using supercritical CO2 and ... [more ▼]

Supercritical fluid extraction (SFE) of polychlorinated dibenzo-p-dioxins (dioxins) from by ash samples, collected at different municipal waste incinerators, was investigated using supercritical CO2 and compared to the classical Soxhlet extraction. Results were correlated to fly ash composition, which is strongly related to the fume purification system used in the incinerators. Fly ash collected at the bottom of the electrostatic precipitator is composed of dust coming from the combustion unit, but also of lime and eventually of activated charcoal injected in the fumes for acids and pollutants removal. When only lime is used for the fume purification, SFE of dioxins from fly ash leads to better results than Soxhlet extraction. The use of a binary cosolvent (trifluoroacetic acid in toluene) greatly increases the percentage recovery. When activated charcoal is used in conjunction with lime for the fume purification, SFE under classical extraction conditions is not powerful enough to extract dioxins, which are strongly adsorbed to the residual activated charcoal. (C) 1998 Elsevier Science B.V. All rights reserved. [less ▲]