Abstract: Components of a mixture are separated by feeding charged molecules of the components into a end surface of a suitable medium, for example a gel. The molecules are drawn in a first direction through the medium by means of an DC electric field, while at the same time being subjected to an alternating voltage with a strongly asymmetric profile in a direction transverse to the first direction. The nonlinear behavior of the electrically-generated migration causes a large number of molecules to migrate transversely out of the medium while only a small number of molecules reach the opposite end surface of the medium. A superimposed DC voltage in the transverse direction selects which of the mixture components migrate all the way through the medium in the first direction. The separated components can be sampled from the opposite end surface and from points on the upper and lower medium surfaces.

Abstract: The invention relates to spatially resolved mass spectrometric measurement and visualization of the distribution of small molecules in a mass range from approximately 150 to 500 Daltons, for example drugs and their metabolites, in thin sections or other two-dimensional samples, preferably with ionization of the molecules by matrix-assisted laser desorption. The invention includes the steps measuring a daughter ion produced by forced decomposition of the molecular ion instead of the ionized analyte molecule itself, the daughter ion having a much better signal-to-noise ratio. The daughter ions are detected in a relatively simple reflector time-of-flight mass spectrometer instead of using an expensive time-of-flight tandem mass spectrometers for the measurement of the daughter ions.

Abstract: The invention relates to ions guided by gas flows in mass spectrometers, particularly in RF multipole systems, and to RF quadrupole mass filters and their operation with gas flows in tandem mass spectrometers. The invention provides a tandem mass spectrometer in which the RF quadrupole mass filter is operated at vacuum pressures in the medium vacuum pressure regime, utilizing a gas flow to drive the ions are through the mass filter. Vacuum pressures between 0.5 to 10 pascal are maintained in the mass filter. The mass filter may be enclosed by a narrow enclosure to guide the gas flow. The quadrupole mass filter may be followed by an RF multipole system, operated at the same vacuum pressure, serving as fragmentation cell to fragment the selected parent ions.

Abstract: In an RF quadrupole ion trap having electrodes to which RF voltages are applied, ions having m/z ratios outside of a predefined narrow range of charge-related masses m/z are removed from the trap by applying a DC voltage pulse to at least one of the trap electrodes to remove from the trap the ions with high values of charge-related masses. The DC voltage pulse is preferably applied in combination with a variation of the RF voltage amplitudes to simultaneously remove from the trap ions of low charge-related masses. The DC and RF voltage amplitudes are changed in such a manner that any excitation of ions having charge-related masses within the predefined range by frequency mixtures is avoided.

Abstract: A supersonic gas jet having gas molecules with substantially equal velocities is formed by directing the gas through a Laval nozzle into an evacuated chamber. A field barrier having a substantially constant height across a cross-section of the supersonic gas jet is formed by respectively applying potentials U2, U3 and U4 to an arrangement of three apertured diaphragms R2, R3 and R4, which are respectively separated by distances d2 and d3, where (U4?U3)/(U3?U2)=d3/d2. The ions in the supersonic gas jet are directed against the field barrier, where ions with a mobility below a mobility threshold are pushed over the field barrier, and where ions with a mobility higher than the mobility threshold are held back by the field barrier.

Abstract: The invention relates to preparing a matrix layer on a sample support for mass spectrometric analysis. An aspect of the invention includes detecting a light signal that is attenuated, reflected or scattered by the matrix layer, and using the light signal to examine the matrix layer or to regulate the preparation of the matrix layer.

Abstract: A dual-stage method is provided for identifying a microbe by, for example, its species or its subspecies. The method includes measuring a mass spectrum of the microbe using a mass spectrometer, calculating indicators for similarities between reference mass spectra in a library and the measured mass spectrum, selecting a group of reference mass spectra similar to the measured mass spectrum, determining a distinguishing weight for each mass signal of the reference mass spectra in the group, where the distinguishing weights emphasize differences between the reference mass spectra in the group, and calculating indicators for similarities between the reference mass spectra in the group and the measured mass spectrum as a function of the distinguishing weights.

Abstract: The invention relates to devices and methods for the acquisition of mass spectra with very high mass resolution in ion cyclotron resonance mass spectrometers and methods to produce the devices. The invention presents cylindrical ICR measuring cells with special electrode geometries to generate harmonic trapping potentials for orbiting ions up to the walls of the cell. Only a single DC trapping voltage has to be applied to create the harmonic trapping potential distribution. The sheath of the cylindrical cell is divided by longitudinal gaps into a multitude of sheath electrodes, which either have to carry layers with resistance profiles able to generate parabolic voltage profiles along the sheath electrodes, or which form sheath electrodes of varying width by parabolic gaps, able to create complicated potential distributions which are harmonic on average for orbiting ions.

Abstract: In a linear ion trap, ions with two polarities are confined radially via an RF potential between the rods comprising the trap. Axially, ions of at least one polarity are confined via DC potentials applied to the elements of the trap or electrodes at the ends of the trap whereas ions of the other polarity are axially confined by a combination of pseudopotentials and/or DC potentials.

Abstract: An electrostatic Kingdon ion trap in which ions can oscillate harmonically in the longitudinal direction, decoupled from their motions in the transverse direction is formed from at least three inner electrodes located inside a hollow outer housing electrode. The inner surface of the housing electrode and the outer surfaces of the inner electrodes are formed so that when a potential is applied between the housing and the inner electrodes, the potential distribution inside the housing contains not only a term for a harmonic potential well in the axial direction, but also a term for the potential distribution in the radial direction, that contains, independent of the axial coordinate, the equations for a family of Cassini curves of at least the third order.

Abstract: A complex protein mixture is analyzed by jointly digesting the mixture, separating the digest peptides chromatographically or electrophoretically, and ionizing the digest peptides eluting from the separation device by an ionizing method that generates multiply charged ions. Digest peptide ions within a pre-selected range of m/z-values are isolated in an RF ion trap and subsequently reduced in their charge state. The charge-reduced ions can be measured with very high sensitivity. By repeating this process with adjacent isolation mass windows within the time duration of each separation peak, it is possible to determine the masses m, the prevalent charge states z, the retention times t, and the intensities i of a huge number of digest peptides of the complex protein mixture in a single separation run.

Abstract: A simplified sample preparation on a sample support for ionization with laser desorption (MALDI or LDCI, for example) includes depositing an analyte material onto a deposition site, providing a sample site which is intended as the substrate for a matrix crystal layer at a distance from the deposition site, and establishing a liquid communication between the deposition site and the sample site. A device for the preparation of samples for ionization with matrix-assisted laser desorption, and a sample support for use with the inventive method are also disclosed.

Abstract: A method is provided for measuring mobility spectrum of ions in an ion mobility spectrometer having an ion source, a modulator, an ion drift region and an ion detector disposed at the end of the ion drift region. The method includes the steps of modulating an ion current from the ion source, and measuring the mobility spectrum, where a predistortion of the continuous modulation function substantially compensates for a distortion created by the modulator. The ion current is modulated with the modulator by varying an instantaneous frequency of a continuous modulation function across a frequency range. The mobility spectrum is measured by correlating the ion current measured at the detector and the modulation function.

Abstract: Analyte ions, particularly biopolymer ions, stored in an RF ion trap are ergodically fragmented by bombarding the analyte ions with collision ions, for example medium-mass, mono-atomic ions having a charge of opposite polarity to the charge of the analyte ions. Since the analyte ions are not fragmented by accelerating and/or exciting them to oscillations, as is the case with conventional collision-induced dissociation, the RF voltage of the ion trap can be set low enough that daughter ions with light charge-related masses that are produced by the fragmentation can also remain trapped in the ion trap.

Abstract: The compensation potentials on the compensation electrodes of an ICR measuring cell are sequentially adjusted so that an ICR measurement with the longest possible usable image current transient is produced. Then, subsequent ICR measurements are made using the ICR cell with the optimally adjusted compensation potentials. Depending on the kind of ion mixture involved, measurements with image current transients from 10 to more than 20 seconds long can be performed, from which mass spectra with a maximum mass resolution without peak coalescence can be obtained.

Abstract: In an analytical spectrometer in which accelerated electrons are used to ionize analytes, a non-radioactive electron source uses a gas discharge to generate the electrons. The gas discharge is located in a substantially hermetic source chamber and the free electrons in the plasma of the gas discharge are accelerated in an electric acceleration region towards a partition wall which separates the source chamber from a reaction chamber. The partition wall is permeable to the accelerated electrons but impermeable to gas in the source chamber so that the electrons penetrate the partition wall into the reaction chamber and generate primary ions that chemically ionize the analytes.

Abstract: In an ion mobility spectrometer, ions are generated, mobility-separated and deposited on a receiver, preferably at spatially separated positions by soft landing or crash landing techniques. The ion mobility spectrometer can be a stand-alone instrument or part of a hybrid analysis instrument. To analyze the deposited ions, the receiver is removed from the vacuum system of the ion mobility spectrometer and introduced into an analytical instrument. Various physical, chemical, and biological analysis techniques and instrumentation can be used, such as mass spectrometry or surface analytical techniques, by selecting a special receiver suitable for the desired analytical technique.

Abstract: A method for the identification and localization of proteins or other biomolecules of a histologic tissue section comprises enzymatically digesting the biomolecules of two similar tissue sections while substantially preserving the biomolecule positions in the tissue sections. Next, a mass spectrometric image of the digest products in one of the tissue sections is acquired. Then, the digest products of the other tissue section are extracted and separated and the mass spectra and daughter ion spectra of all the digest products are acquired. A list of all identifiable biomolecules of the tissue section is created by comparing the mass spectra and daughter ion spectra with spectra in biomolecule structure databases or spectral libraries. Finally, the biomolecules in the list are assigned to digest products of the same mass in the mass spectra used to create the mass spectrometric image of the thin tissue section.

Abstract: In a three-dimensional Paul RF ion trap the ring electrode and end cap electrodes are formed from pairs of pole rods. This multipole rod system is then operated as a linear ion trap with a constant field distribution along the multipole rod system. While the system is operating as a linear ion trap, analyte ions are introduced and stored within the linear ion trap. After the ions have been stored, a single-phase RF voltage is supplied to all rods of a middle segment thus forming a three-dimensional ion trap, thereby collecting the ions in a spherical cloud within this middle segment. The collected analyte ions can then be reacted in the three-dimensional ion trap and the product ions resulting from the reactions can be ejected for mass analysis.

Abstract: A calibration function for time-of-flight mass spectrometers that converts ion times of flight into mass to charge ratios, takes into account not only the time of flight of a specific ionic species, but also the ion signal intensity of that ionic species. Use of the conversion function reduces nonsystematic deviations of the calculated mass values from the true mass values previously experienced in time of flight mass spectrometers.