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Conformers of equine cytochrome c were investigated in the gas phase using a combination of high-field asymmetric waveform ion mobility spectrometry (FAIMS) and hydrogen-deuterium (H-D) exchange. Electrospray generated ions of equine cytochrome c were exposed to a low concentration of [D.sub.2]O vapour while being transported by a flow of nitrogen through a FAIMS device. During this transport period of about 250 ms in the FAIMS analyzer, the various conformers of multiply charged ions of cytochrome c were simultaneously undergoing H-D exchange and being separated from each other. The extent of H-D exchange was calculated from the observed m/z of conformers after exposure to [D.sub.2]O vapour in FAIMS. The complementary nature of these two methods resulted in observations supporting a greater number of conformers (e.g., at least 11 conformers were identified for the +16 charge state) than would be expected by analyzing the FAIMS data and the H-D exchange data independently. Key words: FAIMS, H-D exchange, mass spectrometry, protein conformations, electrospray ionization. On a Etudie les conformeres du cytochrome c equin en phase gazeuse en utilisant une combinaison d'Echange d'hydrogene et de deuterium et de spectrometrie de la mobilite ionique, de forme d'onde asymetrique et a haut champ (<< FAIMS >>). Les ions generes par electronebulisation du cytochrome c equin sont exposes a une faible concentration de vapeur de [D.sub.2]O pendant qu'ils sont entraines par un courant d'azote a travers un analyseur FAIMS. Au cours de la periode de 250 ms de ce transport dans l'analyseur FAIMS, les divers conformeres des ions du cytochrome c a charges multiples subissent des echanges H-D simultanes et se separent les uns des autres. On a calcule le degre d'echange H-D a partir des valeurs m/z observees pour les conformeres apres leur exposition 5 la vapeur de [D.sub.2]O dans l'analyseur FAIMS. La nature complementaire de ces deux methodes permet de faire des observations qui suggerent l'existence d'un beaucoup plus grand nombre de conformeres (par exemple, on a identifie au moins 11 conformeres pour l'etat de charge +16) que le nombre attendu sur la base d'une analyse des donnees FAIMS et des donnees d'echange H-D prises independamment. Mots cles : << FAIMS >>, echange H-D, spectrometrie de masse, conformations de proteines, ionisation par electronebulisation. [Traduit par la Redaction], Introduction The ability to produce intact ions from large molecules (1, 2) has led to the development of several methods for studying biomolecular ions in the gas phase (3, 4). [...]

Examines tryptic peptides of pig hemoglobin using a combination electrospray ionization, high-field asymmetric waveform ion mobility spectrometry, and mass spectrometry (ESI-FAIMS-MS). Comparison of mass spectra collected with ESI-MS and ESI-FAIMS-MS; Identification of isobaric interferences; Improvement in signal to background.

Investigates the focusing of ions at atmospheric pressure and room temperature in a high-field asymmetric waveform ion mobility spectrometer (FAIMS). Principle of operation of FAIMS; Dependence of sensitivity on the dispersion voltage; Modeling of the ion motion in the FAIMS; Theory of ion focusing in FAIMS.

Describes a more efficient furnace atomization plasma ionization mass spectrometry (FAPIMS) interface. Use of a sampler-skimmer interface for ion sampling; Characterization of plasma species; Potential of the plasma to ionize.

Studies electrospray ionization using high-field asymmetric waveform ion mobility spectrometry (FAIMS). Determination of the electrospray ions separated by FAIMS; Theory of FAIMS; Electrospray FAIMS-mass spectrometry spectra of several compounds; Investigation of the linearity of response to electrospray FAIMS-mass spectrometry.

Presents a mass spectrometric characterization of a high-field asymmetric waveform ion mobility spectrometer (IMS). Applications of IMS; Difference from the high-field asymmetric waveform IMS; Factors affecting the sensitivity and peak locations in the voltage spectra.

Describes a commercially available ion mobility spectrometer which was interfaced to a custom-built linear time-of-flight (TOF) mass spectrometer for the examination of electrospray-generated plumes. Description of ionic species; Information on the ion mobility.

The mechanism of the collision-induced fragmentation of peracetylated methyl-α-D-glucopyranoside was investigated using deuterium-labelled acetates and sequential mass spectrometry. Loss of the substituent at C(1), the anomeric carbon, yields an ion of m/z 331, [C14H19O9]+. This ion further dissociates via two pathways, the first including m/z 271, [C12H15O7]+, 169, [C8H9O4]+ and 109, [C6H5O2]+, and the second including m/z 211, [C10H11O5]+, 169, [C8H9O4]+ and 127 [C6H7O3]+. The first path proceeds via loss of acetate at C(3), followed by a single-step concerted loss of acetates from C(2) and C(4), and ending with loss of acetate from C(6). The second path proceeds predominantly via loss of acetates from C(3) and C(4), elimination of ketene from the C(2)-acetate and finally loss of ketene from the acetate at C(6). This path is also characterized by an ill-defined series of parallel decomposition reactions involving acetates from other sites on the molecule. At low collision energy, and in the absence of collision gas (unimolecular reaction conditions), the former pathway predominates; m/z 331 dissociates via loss of acetate at C(3), followed by a single-step concerted loss of acetates from C(2) and C(4). [ABSTRACT FROM AUTHOR]

Careful analysis is made of the accuracies possible when gaseous ion mobilities are determined from data obtained by combining electrospray ionization (ESI), high-field asymmetric waveform ion mobility spectrometry (FAIMS) at atmospheric pressure and room temperature, and mass spectrometry (MS). New results are reported for the mobilities of positive and negative amino acid ions in air at elevated values of E/N, the ratio of the electric field strength to the gas number density. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Presents an experiment monitoring the presence of various toxins, including the paralytic shellfish poisons (PSPs) in fish and shellfish using liquid chromatography. Occurrence of red tide; Focus on increased problem of toxic shellfish; Areas where PSP infestation has been reported; Risk of PSPs in humans; Analysis of PSP saxitoxin; Description of ]liquid chromatography.

Examines the quantification and measurement of amphetamine, methamphetamine and methylenedioxy derivatives in a human urine matrix. Use of solid-phase microextraction and high-field asymmetric waveform ion mobility spectrometry; Observation of chromatographic separation; Effects of amphetamine and methamphetamine on health.

Approaches to separation and characterization of ions based on their mobilities in gases date back to the 1960s. Conventional ion mobility spectrometry (IMS) measures the absolute mobility, and field asymmetric waveform IMS (FAIMS) exploits the difference between mobilities at high and low electric fields. However, in all previous IMS and FAIMS experiments ions experienced an essentially free rotation; thus the separation was based on the orientationally averaged cross-sections Omega(avg) between ions and buffer gas molecules. Virtually all large ions are permanent electric dipoles that will be oriented by a sufficiently strong electric field. Under typical FAIMS conditions this will occur for dipole moments >400 D, found for many macroions including most proteins above approximately 30 kDa. Mobilities of aligned dipoles depend on directional cross-sections Omega(dir) (rather than Omega(avg)), which should have a major effect on FAIMS separation parameters. Here we report the FAIMS behavior of electrospray-ionization-generated ions for 10 proteins up to approximately 70 kDa. Those above 29 kDa exhibit a strong increase of mobility at high field, which is consistent with predicted ion dipole alignment. This effect expands the useful FAIMS separation power by an order of magnitude, allowing separation of up to approximately 10(2) distinct protein conformers and potentially revealing information about Omega(dir) and ion dipole moment that is of utility for structural characterization. Possible approaches to extending dipole alignment to smaller ions are discussed.